No Disk Space

Actually this question is related to both Win98 & win2k server. Recently I installed a clean copy of windows 98. There was more than 1.25 GB free space. I just accessed Internet thro LAN & I did’nt work much in that PC. Now if I Start the PC, it says that U’r hard disk is full. There is only 10 MB in my C drive. Since 2 days I have the same problem with win2k Server also. I just don’t understand how my 30 GB hard disk can become so full by hardly using it. I have Norton Antivirus in both the pcs. In Win2k server I recently installed Internet Explorer 6. If I click the icon it takes 30 mins for the application to Open. Strange…….. Anyone, help me please.