Desktop Display Icons Changing from "normal" to large

Inspiron 2650.  Booted up last night and icons on desktop display came up normally, a few seconds later screen turned black, and a few seconds after that icons came back but much larger. Internet pages also large, i.e. one page will not fit on screen - have to navigate around with the elevators, which normally do not have to do. Did a system restore - same problem. Verified that display icon box was unchecked for "large icon." Did everything I knew how to solve problem to no avail.

When I booted this morning, the large icons came up, black screen for a few seconds, then back to "normal."

Everything else on computer seems to be working fine. 

Anyone know what's causing this? I am not a techie - any help would be greatly appreciated. Thanks in advance.