Assuming you are running Windows XP, I would suggest unloading all customization programs to restore the default Windows XP theme.
This would include the following:
1 - If using IconPackager, perform the following: "Start IconPackager > Tools menu > Restore all Icons > click "Yes" to confirm in pop-up dialog > click the "OK" button at bottom of IconPackager window to apply.
2 - If using WindowBlinds, perform the following: "Start WindowBlinds > select "Unload WindowBlinds" > click "Yes" to confirm in the pop-up dialog > wait a few seconds while WindowBlinds unloads, leaving the "Windows Classic" look.
3 - Right-click any widgets that you have running > select Preferences > deselect any options telling the widget to run at startup, then close the widget(s).
4 - If running DesktopX or ObjectDock, just unload the programs.
5 - If running LogonStudio or Bootskin, start the program(s) and select the default Windows XP themes.
6 - If running CursorXP, start CursorXP and select the "Disable all" at the bottom of the CursorXP tab to restore the default mouse pointers.
7 - Right-click the desktop > Properties > Themes tab > select "Windows XP" in the Theme drop-down list > click "Apply" to complete the restoration of the default Windows XP theme.
8 - Restart your computer, and test the functionality of your computer with the customization softwares unloaded and running on the default Windows XP theme.
If you find the flickering issue still persists, you may be looking at a driver issue, or possible hardware issue.
If the flickering goes away, you can then try reapplying your customization software themes until you find the issue (it should be the last software applied before the flickering reappears).
I would suggest the following order for reapplication:
- IconPackager
- WindowBlinds
- ObjectDock
- Widgets
- DesktopX
- CursorXP
- LogonStudio
- Bootskin (if used)
- Windows FX (if used - this one can be very heavy on video resources)
- Any others you may be using (Right-click, IconX, etc.)
Post again as needed for additional help. 
