Load Recovery Console.
do a chkdsk /f to fix any file system errors
Do a sfc /scannow to check all your windows files are ok
Download a disk diagnostic utility from the manufacturer and use that to check the health of your HDD.
If its got some bad results from the disk diagnostic test, then your HDD is unreliable and should be backed up and replaced asap.
Failing all that, you can try a windows Repair, which will overwrite the windows but will allow you to keep your data intact. Its advisable to do a backup of your important files if you can (by slaving it to another PC or using a live OS cd) before performing such a big system change.
Unless the two PCs you have are similar/same spec'd and motherboard (unless you try and boot into Safe Mode) then windows would probably give you an error trying to load, due to motherboard drivers being different.
recagent.sys is part of your modem software set..
Does safe mode work?