1. When did the issue start?
2. Are you able to open other programs?
2. Do you get any error messages or error codes?
Perform a system file scan to check for any system file corruptions.
a. Click Start, All programs and then Accessories. Click Command Prompt.
b. In the Command Prompt window type “sfc /scannow” (without quotes) and then press Enter.
c. After the scan has completed, close the command prompt window, restart the computer and check for the issue.
For addition information, you may refer the following link:
Description of Windows XP and Windows Server 2003 System File Checker (Sfc.exe)
You may also try to boot in safe mode and see if the issue occurs.
You may refer the following link to boot in Safe mode.
Hope this information is helpful.