我的显示器看起来像一个垂直分屏，上部 ¾ 显示正常内容，而下部 ¼ 似乎重复/镜像上部。有人能帮我禁用它吗？
这是 Xubuntu 14.04。
3.13.0-45-generic trusty
Screen 0: minimum 320 x 200, current 1280 x 1024, maximum 4096 x 4096
VGA-1 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 338mm x 270mm
1280x1024 60.0*+ 75.0
00:00.0 RAM memory: NVIDIA Corporation C51 Host Bridge (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0
Capabilities: <access denied>
00:00.1 RAM memory: NVIDIA Corporation C51 Memory Controller 0 (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: 66MHz, fast devsel
00:00.2 RAM memory: NVIDIA Corporation C51 Memory Controller 1 (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: 66MHz, fast devsel
00:00.3 RAM memory: NVIDIA Corporation C51 Memory Controller 5 (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: 66MHz, fast devsel
00:00.4 RAM memory: NVIDIA Corporation C51 Memory Controller 4 (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0
00:00.5 RAM memory: NVIDIA Corporation C51 Host Bridge (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0
Capabilities: <access denied>
00:00.6 RAM memory: NVIDIA Corporation C51 Memory Controller 3 (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: 66MHz, fast devsel
00:00.7 RAM memory: NVIDIA Corporation C51 Memory Controller 2 (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: 66MHz, fast devsel
00:02.0 PCI bridge: NVIDIA Corporation C51 PCI Express Bridge (rev a1) (prog-if 00 [Normal decode])
Flags: bus master, fast devsel, latency 0
Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
Capabilities: <access denied>
Kernel driver in use: pcieport
00:04.0 PCI bridge: NVIDIA Corporation C51 PCI Express Bridge (rev a1) (prog-if 00 [Normal decode])
Flags: bus master, fast devsel, latency 0
Bus: primary=00, secondary=02, subordinate=02, sec-latency=0
Capabilities: <access denied>
Kernel driver in use: pcieport
00:05.0 VGA compatible controller: NVIDIA Corporation C51G [GeForce 6100] (rev a2) (prog-if 00 [VGA controller])
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 42
Memory at fd000000 (32-bit, non-prefetchable) [size=16M]
Memory at d0000000 (64-bit, prefetchable) [size=256M]
Memory at fc000000 (64-bit, non-prefetchable) [size=16M]
Expansion ROM at febe0000 [disabled] [size=128K]
Capabilities: <access denied>
Kernel driver in use: nouveau
00:09.0 RAM memory: NVIDIA Corporation MCP51 Host Bridge (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0
Capabilities: <access denied>
00:0a.0 ISA bridge: NVIDIA Corporation MCP51 LPC Bridge (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0
00:0a.1 SMBus: NVIDIA Corporation MCP51 SMBus (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: 66MHz, fast devsel, IRQ 5
I/O ports at 1000 [size=64]
I/O ports at 6000 [size=64]
Capabilities: <access denied>
Kernel driver in use: nForce2_smbus
00:0b.0 USB controller: NVIDIA Corporation MCP51 USB Controller (rev a2) (prog-if 10 [OHCI])
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 23
Memory at febde000 (32-bit, non-prefetchable) [size=4K]
Capabilities: <access denied>
Kernel driver in use: ohci-pci
00:0b.1 USB controller: NVIDIA Corporation MCP51 USB Controller (rev a2) (prog-if 20 [EHCI])
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 22
Memory at febdfc00 (32-bit, non-prefetchable) [size=256]
Capabilities: <access denied>
Kernel driver in use: ehci-pci
00:0d.0 IDE interface: NVIDIA Corporation MCP51 IDE (rev a1) (prog-if 8a [Master SecP PriP])
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0
[virtual] Memory at 000001f0 (32-bit, non-prefetchable) [size=8]
[virtual] Memory at 000003f0 (type 3, non-prefetchable)
[virtual] Memory at 00000170 (32-bit, non-prefetchable) [size=8]
[virtual] Memory at 00000370 (type 3, non-prefetchable)
I/O ports at ffa0 [size=16]
Capabilities: <access denied>
Kernel driver in use: pata_amd
00:0e.0 IDE interface: NVIDIA Corporation MCP51 Serial ATA Controller (rev a1) (prog-if 85 [Master SecO PriO])
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 21
I/O ports at e800 [size=8]
I/O ports at e480 [size=4]
I/O ports at e400 [size=8]
I/O ports at e080 [size=4]
I/O ports at e000 [size=16]
Memory at febdd000 (32-bit, non-prefetchable) [size=4K]
Capabilities: <access denied>
Kernel driver in use: sata_nv
00:10.0 PCI bridge: NVIDIA Corporation MCP51 PCI Bridge (rev a2) (prog-if 01 [Subtractive decode])
Flags: bus master, 66MHz, fast devsel, latency 0
Bus: primary=00, secondary=03, subordinate=03, sec-latency=64
Capabilities: <access denied>
00:10.2 Multimedia audio controller: NVIDIA Corporation MCP51 AC97 Audio Controller (rev a2)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device b010
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 23
I/O ports at d800 [size=256]
I/O ports at d400 [size=256]
Memory at febdc000 (32-bit, non-prefetchable) [size=4K]
Capabilities: <access denied>
Kernel driver in use: snd_intel8x0
00:14.0 Bridge: NVIDIA Corporation MCP51 Ethernet Controller (rev a1)
Subsystem: Micro-Star International Co., Ltd. [MSI] Device 7228
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 20
Memory at febdb000 (32-bit, non-prefetchable) [size=4K]
I/O ports at dc00 [size=8]
Capabilities: <access denied>
Kernel driver in use: forcedeth
00:18.0 Host bridge: Advanced Micro Devices, Inc. [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration
Flags: fast devsel
Capabilities: <access denied>
00:18.1 Host bridge: Advanced Micro Devices, Inc. [AMD] K8 [Athlon64/Opteron] Address Map
Flags: fast devsel
00:18.2 Host bridge: Advanced Micro Devices, Inc. [AMD] K8 [Athlon64/Opteron] DRAM Controller
Flags: fast devsel
00:18.3 Host bridge: Advanced Micro Devices, Inc. [AMD] K8 [Athlon64/Opteron] Miscellaneous Control
Flags: fast devsel
Kernel driver in use: k8temp