Download the free PassMark DiskCheckup software.
Check the SMART Info, paying particular attention to C4 (Reallocation Event Count), C5 (Current Pending Sector Count ) and C6 (Uncorrectable Sector Count). These should typically be 0.
Then run the Extended Disk Self Test.
If the disk passes the test you'll know at least that it's more likely a software problem and not a physical disk problem.
I did have some VSS errors that in my case were directly attributable to a prematurely failing disk.
Steve
Thanks for the link, very useful utility, current version are a bit different now:
Reallocated Sector Count=Raw Value: 0
Current Pending Sector Count=Raw Value: 0
Uncorrectable Sector Count=Raw Value: 0
Reported Uncorrectable Errors=Raw Value=1996
Power Cycle Count=Raw Value: 2533
UltraDMA Cyclic Redundancy Check Error Count=Raw Value: 0
High Fly Writes Error=Raw Value=24
Command Timeout= Raw Value: 21(Aborted operations due HDD timeout. If this value is far above zero, most likely there will be some serious prob w/power supply or oxidized data cable)