Look into a folder under
C:\WINDOWS\OPTIONS\CABS
if you see a bunch of files there and they total around 160MB
Thats your Windows installation files, make a copy of that onto a CD if possible, then
Restart computer
Press F8
Choose MS-DOS mode
Type in :
CD C:\WINDOWS\OPTIONS\CABS
and type SETUP
it should start the 98 installation and hopefully solve your problem
* ADDED NOTES *
'what' just gave me an idea, try this first
Start the PC
Press F8 and choose MS-DOS from the menu
Once in DOS
Type in
SCANREG /RESTORE (space between G and / )
This should bring up an menu
Pick a date to roll back the registry
if you can get on say few days or even few weeks, try it
Restart after its restored
Hopefully you may get into Windows
the error of MSVCRT is a common error from memory, as at the time, many applications utilize this to run their software, so sometime is impossible to work out which is causing it unless it pinpoints the module its linked to