from your log files:

===
2013/06/11 20:57:21|I/O Errors detected on unit S001. To prevent data loss it is recommended to shut down the system.

2013/06/11 20:57:26|[297993.980680] Call Trace:
2013/06/11 20:57:26|[297993.980683] [<ffffffff81138131>] ? ext3_ordered_writepage+0x1e1/0x200
2013/06/11 20:57:26|[297993.980685] [<ffffffff81138131>] ? ext3_ordered_writepage+0x1e1/0x200
2013/06/11 20:57:26|[297993.980689] [<ffffffff8104590c>] ? warn_slowpath_common+0x8c/0xc0
2013/06/11 20:57:26|[297993.980692] [<ffffffff81138131>] ? ext3_ordered_writepage+0x1e1/0x200
2013/06/11 20:57:26|[297993.980695] [<ffffffff8109a8fa>] ? __writepage+0xa/0x30
2013/06/11 20:57:26|[297993.980697] [<ffffffff8109ac06>] ? write_cache_pages+0x1a6/0x350
2013/06/11 20:57:26|[297993.980699] [<ffffffff8109a8f0>] ? __writepage+0x0/0x30
2013/06/11 20:57:26|[297993.980703] [<ffffffff8117faef>] ? journal_stop+0x1af/0x290
2013/06/11 20:57:26|[297993.980706] [<ffffffff810ee975>] ? writeback_single_inode+0xc5/0x2d0
2013/06/11 20:57:26|[297993.980708] [<ffffffff810eee3c>] ? writeback_sb_inodes+0xac/0x130
2013/06/11 20:57:26|[297993.980710] [<ffffffff810ef40b>] ? writeback_inodes_wb+0xfb/0x130
2013/06/11 20:57:26|[297993.980712] [<ffffffff810ef631>] ? wb_writeback+0x1f1/0x260
2013/06/11 20:57:26|[297993.980714] [<ffffffff810ef7f5>] ? wb_do_writeback+0x155/0x160
2013/06/11 20:57:26|[297993.980717] [<ffffffff810ef837>] ? bdi_writeback_task+0x37/0x130
2013/06/11 20:57:26|[297993.980720] [<ffffffff81592695>] ? _raw_spin_lock+0x5/0x10
2013/06/11 20:57:26|[297993.980723] [<ffffffff810a7060>] ? bdi_start_fn+0x0/0x100
2013/06/11 20:57:26|[297993.980725] [<ffffffff810a70e4>] ? bdi_start_fn+0x84/0x100
2013/06/11 20:57:26|[297993.980727] [<ffffffff810a7060>] ? bdi_start_fn+0x0/0x100
2013/06/11 20:57:26|[297993.980730] [<ffffffff8105c4b6>] ? kthread+0x96/0xa0
2013/06/11 20:57:26|[297993.980734] [<ffffffff8100aa64>] ? kernel_thread_helper+0x4/0x10
2013/06/11 20:57:26|[297993.980736] [<ffffffff8105c420>] ? kthread+0x0/0xa0
2013/06/11 20:57:26|[297993.980738] [<ffffffff8100aa60>] ? kernel_thread_helper+0x0/0x10
===

This is likely an issue with the file system on the boot media. You can verify if is the data array or not by checking which unit is being used for your volume group in the webGUI, CONFIGURATION-->Volume manager.

If it is the boot media, run the repair file system command from the console at CNTRL+ALT+X menu.
If this does not help consider re-installing the OS and/or replacing the boot drive.
===
Disk /dev/sda: 250.0 GB, 250059350016 bytes
39 heads, 62 sectors/track, 201983 cylinders
Units = cylinders of 2418 * 512 = 1238016 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 1616 1953125 c W95 FAT32 (LBA)
===