我是 Ubuntu 新手。在 Acer Inspire E5 上完全重新安装 14.04 LTS 后，硬盘无法识别为可启动设备，尽管通常情况下可以识别。从 USB 启动 Ubuntu 并运行sudo fdisk -l会产生以下结果：
WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted.
Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x81d6cb14
Device Boot Start End Blocks Id System
/dev/sda1 * 1 1953525167 976762583+ ee GPT
Partition 1 does not start on physical sector boundary.
Disk /dev/sdb: 4018 MB, 4018143232 bytes
255 heads, 63 sectors/track, 488 cylinders, total 7847936 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0021f04b
Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 7847935 3922944 c W95 FAT32 (LBA)
这与我可以使用的一个正常工作的 ubuntu 笔记本电脑上的输出在某些方面有所不同，该笔记本电脑有三个分区，并且不使用 GPT。但是我不知道哪个差异导致了问题，或者为什么我的笔记本电脑突然无法从硬盘启动（在发生这种情况之前我没有摆弄分区），也不知道如何修复它。我特别想知道笔记本电脑无法启动，/dev/sda1尽管 fdisk 显示它可以启动（我使用 cfdisk 设置了这一点）。
我的分区表是否存在明显缺陷，导致无法从硬盘启动？
编辑：的输出sudo gdisk -l如下：
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: present
Found valid GPT with protective MBR; using GPT.
Disk /dev/sda: 1953525168 sectors, 931.5 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): DAE150BD-1F2D-450E-BAA4-551D3ACA8047
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 1953525134
Partitions will be aligned on 2048-sector boundaries
Total free space is 3437 sectors (1.7 MiB)
Number Start (sector) End (sector) Size Code Name
1 2048 1050623 512.0 MiB EF00
2 1050624 1936922623 923.1 GiB 8300
3 1936922624 1953523711 7.9 GiB 8200