It sounds as though you have some corrupted files on the hard drive or a program that that has become unstable. Windows 98 has a built in system which will prevent it from loading normally until the corrupted files have been dealt with.
Try the following.
1) Boot in Safe Mode. This will only load essential programs.
2) Go to start - Programs - Accessories - System Tools - click Scan Disk and follow the prompt. This will run a scan and either automatically repair files or tell you what they are.
3) Click Internet Explorer, usually from an icon on the desktop. At the top of the screen click Tools - Internet Options - Settings - View Files. When the window opens, delete all the files in this folder.
4) Go back to system tools again and select Defragment Drive, follow the prompts.
5) Restart the computer. If it still does not start normally, try a selective start up. This will allow you to disable all start up programs and start in normal mode. You should be able to enable each program one by one until the offending program is found.
TEKBABE, January 2008