So you mean when you are going to the desktop, first starting up the computer, a lot of windows (for other things) flash on the screen before you get to the desktop? Or is it just the display is blinking?
OK, then you need to be checking the computer for viruses, malware and any bad recently added programs first.
Should none of these turn up anything, next you would go to "Start" and then in the search bar type "msconfig" (without the quotes).
NOTE: Be extremely careful while in here. Way to many people will just start changing things, deactivating things, removing things, etc., and do way more damage to the computer than they actually started with. So do not change anything without being absolutely sure what it is you are changing.
In msconfig you want to go to the "Startup" tab and check what is set to auto run when you turn on the computer.
After any changes you make in there, once saved, then reboot (turn off and back on) the computer.
Hmm.. Try loading in "Safe Mode" and see if the things flash by then or not.
How to enter "Safe Mode" when booting the computer.
In Windows 8 and 10...
As your computer restarts, press F8 (possibly a few times) to enter "Safe Mode"
a. Press the "F4" key to Enable "Safe Mode".
(The computer will then start in "Safe Mode" with a minimal set of drivers and services.)
b. Press the "F5" key to Enable "Safe Mode" with Networking.
( Once "Safe Mode" with Networking starts, Windows is in Safe Mode, with additional network and services for accessing the Internet and other computers on your network.)
c. Press the "F6" key to Enable "Safe Mode" with Command Prompt.
(In "Safe Mode" with "Command Prompt" starts Windows in Safe Mode, with a Command Prompt window instead of the Windows interface. This option is mostly only used by IT professionals.)
Now sign in to the computer with your account name and password. (If you have one set.) When you are finished troubleshooting, you can exit "Safe Mode" restarting your computer.
In Windows 7/Vista/XP...
1. Immediately after turning on the computer, or restarting it (usually after you hear your computer beep), tap the F8 key, repeatedly, in 1 second intervals.
2. The computer will then display hardware information and run a memory test.
3. Next the "Advanced Boot Options" menu will appear.
4. In the "Advanced Boot Options" menu use the arrow keys to select "Safe Mode" or "Safe Mode with Networking" and press ENTER.