Windows 98 Problems

I have recently brought out my old Gateway computer and hooked it up via wireless router and have had no problems until yesterday when I had to re-boot. The problem was no mouse control/functions and the screen color was way off. I have the installation cd's and have re-installed a few times before so that is what I did. This time however (after a second and third re-install) I can not get what updates that are available to install. No biggie, simple surfing is still working but, I would like to put on Yahoo Messenger, or even more simple the Google Toolbar. No go, it says I need to free up disk space or file is corrupt. I have ran scan disc, maint. wizard etc. So in short I can't even install simple fix tools. Not even from the Gateway site.

Any help please!!!!!!! Thx.