Greetings,so my windows suddenly started freezing at the start-up screen for no apparent reason...It keeps trying to run chckdisk too but the problem still remains(i tried defragmentation,virus scan etc...)Safe mode ain't working either . Also this happened right after i ran windows 7 instead of windows xp(i have 2 hard drives on 1 pc). Sometimes it does start but i get c++ errors and something about nvmctray.dll not being able to launch also windows has the ''classic look''. Anyone knows how to solve this issue?

Try to perform a clean boot, follow the steps below:
1. Click Start, type msconfig in the Start Search box, and then press ENTER.
If you are prompted for an administrator password or for a confirmation, type the password, or click Continue.
2. On the General tab, click Selective Startup.
3. Under Selective Startup, click to clear the Load Startup Items check box.
4. Click the Services tab, click to select the Hide All Microsoft Services check box, and then click Disable All.
5. Click OK.
6. When you are prompted, click Restart.
7. After the computer starts, check if it works normally.