Shut Down, Restart, "LOGGING OFF" HELP!

HI I have recently Purchased A Inspiron 1520, Intel Core 2 Duo T7100, 1.8GHz, 800Mhz, 2M L2 Cache I just ran into this problem over the weekend and im getting more than a little frustrated with it/VISTA Everytime I Shut Down or Restart my system it hangs in the logging off screen and it will not shut down, I have not installed any new software, the only thing that i had to install was a reinstall of my drivers for my cd/dvd drive (for some strange reason they werent being detected) I have ran poratable software programs like PCCheckUp so see if it could resolve the issue but it has not Im getting very frustrated with this issue because I do not like to hard boot my system everytime i try to shut down or restart infact i did a restart exactly 20 minutes ago and my system is still logging off Please help