Win7 has become nearly unresponsive

My girlfriends laptop recently started having strange problems. I've tried many things to fix it but cannot figure out what the problem is. As of now the symptoms are:
90% of the time after logging in it will slowly log in and get to the desktop and look completely normal.

The other 10% of the time it will go to a black screen with just the mouse arrow showing. After a while sometimes it will show the desktop.

After getting to the desktop it will either not open any programs or even the start menu or it will work on it for a long time and then open it. If a program does open its virtually unresponsive with the same sort of behavior.

It runs in safe mode and everything works fine, except regular Internet explorer. I have to run Internet explorer 64-bit.

System restore didn't fix the problem. Nor did chkdisk, or a clean boot. (For the chkdisk and the clean boot, I followed a troubleshooting guide. Maybe I did it wrong.)

As for what caused it I'm not sure or even when it first started. It may have been a Microsoft update, or my girlfriend said the battery died and when she charged it and used it next it was like this.

I'm lost and help would be most appreciated.