My son has an IBM ThinkPad laptop with Win98. Recently, he loaded a game (unknown to me) that made a switch setting somewhere. Here is the problem: During boot up, the Windows 98 screen appears for a few seconds, then goes into a DOS window with C:\>Windows\ and the cursor sits an blinks as in the old DOS days. Have looked at the config.sys and autoexec.bat, autoexec.ini and some of the other files with similar names. I don't see anything that would have set the switch any other way. One time, while pounding on the F8 key, Windows allowed me the menu to start in Safe mode. I did delete some programs, but that didn't help, either. Will look at it one more time tonight before I take it to the shop tomorrow.
Thanks for your input.