disk.sys is a microsoft pnp disk file
partmgr.sys is of course a partition management file
sahdad64.sys is known to be a saitek HDD filter driver
These things either can be some kind of malware, a recently installed software or possibly your hard drive.
Seeing as you can not boot up windows, you can try to get the diagnostic software from your hard drive manufacture for DOS and boot up to that cd and do a diagnostic test on your hard drive
There are several malware scan programs that you can run outside of windows by using a boot disk too.
You can get the Kaspersky Rescue disk 10 from here
Kaspersky Rescue Disk 10