Welcome to the forums!
This is what I would do:
Go to add/remove programs and look for suspicious programs, remove all suspicious programs.
Tell us 'who' stole your browser, and report him to the police (J/K about the last part
).
You don't need a bootdisk to format your drive.....
1) Insert Win98 CD into drive.
2) On boot enter BIOS (Usualy by holding Delete).
3) Set boot device to CD-ROM.
4) Exit and save changes.
5) After POST you'll see 3 options:
..1) Install Windows
..2) Boot With CD-ROM Support
..3) Boot Without CD-ROM Support
(It may look slightly different, just Boot
With CD-ROM support)
When it's done loading drivers and such you should be at the A:\ Prompt
Type
X: and hit enter (Were X stands for the drive letter of your CD-ROM drive).
Type
cd win98 and hit Enter (8 might be an x, but I'm pretty sure that's only with WinME).
Type
format x: and hit Enter (Were X stands for the drive letter of the drive you want to format, probably C).
When it's done formatting you can give the partition a name (You can always change it), restart and choose
Install Windows when the list with 3 options come up.
If you want to speed up the formatting you could ad /q (Which will perform a quick format), so it would look like this: format c: /q