Autocheck.exe/Autochk.exe is the boot-time version of Chkdsk. It causes an automatic check of each partition. If it's missing, you could get the error....OR...if the partition is damaged...maybe.
Can you start the computer in normal Windows? If not, have you tried using the "Last Known Good" option when you boot?:
How to load last known good configuration.
Are you using Partition Magic on that machine...It could be causing an issue.
Hope this helps.
When I start the computer the screen turns black and says auto check not found-skipping auto check.Then finishes booting up.OS W2K