Maybe you have too much stuff trying to start with windows. Get rid of some of the stuff in your tray. Check system config/start up and see how many boxes you have checked.
Run CCleaner and do the Clean and Registry portions both.
https://www.piriform.com/ccleaner
Update your virus pgm and run a FULL virus scan.
Run Malwarebytes and do a full malware scan. https://www.malwarebytes.org/
If still no joy, then a clean install of Win7 may be your only hope. Do you have an installation disk, or were you planning on using the restore partition to return it to as-bought condition?