so, a few days ago, I had a weird advertisemant pop up over my window, (accually in my window) covering the entire webpage, though it had a skip button, I've ben dealing with this every once in a while up untill now, Now it is coming up at every webpage I open, (i.e. youtube facebook even bethesda, and other forum sites.) I have the free microsoft anti-virus software and I ran a full scan and it said everything was fine, I have cleaned my temp files and cookies. Now I have no clue what I should do...... so now defeated, I came to you, to ask for help.

do a scan with http://www.malwarebytes.org/

Download Malwarebytes Anti-Malware
Go into safemode
Do a full scan with malwarebytes

If that doesn't get it then the only other thing I can think of is to just wipe your harddrive clean.

Spybot S & D is also a great choice to fix these pesky problems.

I feel stupid saying this but, how do I go into safe mode?

reboot your computer and keep tapping the F8 key while it turns on.

Anti-virus scanners are almost useless after infection, unless they detect the malware and quarantine it. Dedicated malware cleaner are much more effective in cleaning systems after infection.

Try scanning with MBAM, (link): http://www.malwarebytes.org/

However, if you have infected by a Trojan, it can be very difficult to completely remove it. Trojans themselves can infect you with other malware causing a loop of multiple infections.

edit: Wow I need to post more quickly

well, I did a scan, and so far it's not happenning anymore, though malwarebytes never said it found anything.......

It might just be an ad. I get "randomly" on certain sites from gamerDNA (its an ad for Best Buy)...

This guy is one of the best techies on BGSF. Listen to him.