X-ray like color?

I know nothing (no-thing) about computers. I shut it down yesterday afternoon, came home last night, turned it on and the wallpaper (picture of granddaughter)looks like a color spotted x-ray. Had a problem connecting to internet. Kept getting "Error 630" something about modem. Followed directions and modem seemed to be okay. Kept trying and finally got connected again. Shut down last night. Hoped it would fix its self but had the same problem this afternoon. Screen display is too large for my monitor. I have to keep moving it over with the cursor to see all I need to see and all pictures look the same as my wallpaper. All the print is clear and the "Windows 98" window is clear. Do I need to load it all up and head to the computer guy tomorrow or is there something simple that I could do? Any help would be appreciated.