1. Run a Malware/Virus Scan.
2. Remove java and install the latest one if you haven't already (Or install and older one to see if it changes and runs any smoother.
3. Search your installed files and browser add-ons & extensions for software you don't recall installing.
4. System clean up (Defragment) your system.
5. Delete all possible junk files you don't need.
6. Update video/display/sound and board drivers if updates are available.
7. Try changing the resolution.
8. Create a new user on your computer and attempt to play the game on it and see if the same errors occur.
8. System restore is always a good choice.
9. Clean your System Registry and remove outdated files/shortcuts.
10. Check your downloads folder to see if you have recently installed a new program or such and if possible uninstall it and see if it makes any difference, some things can cause the game to lag a lot such as skype or windows media player.
11.Reinstall Windows - If you have an Installation Disc available this is always a good last resort, just be sure to back up any files you don't want to permanently lose on discs/flash drives or cloud storage on outlook and such.
12. Run windows update and install any possible updates - also take a look through the update history and see if anything failed to update, if something did, find it and attempt to update it again as failed updates can cause serious issues sometimes.
I don't know what else to suggest.
Software you could try using to "Clean Up".
Tune up utilities (If it still exists).
If you don't already have an anti-virus try Avast or Microsoft Security Essentials.
Advanced System Care (Free Edition).