Try
Windows Update
Try
this to change the sync speed of your clock
To check if it is the CMOS battery...
When you boot your computer, go boot into the bios (usually del or f2 during bootup)
Check the system time there. Is it correct?
If not, set it, and then save and exit the bios
Once you do that check the time in Windows. Is it correct?
Reboot the computer and get back into the bios. Is the time still correct?
If the time changes again after this second reboot you might need to change the CMOS battery on your motherboard.
Because you have a laptop, this is harder for you if the CMOS is running low.
Some laptops have a special easy to reach compartment, while others you have to open up.
If the computer is under warranty, you could be able to call up Dell and ask them what's up. CMOS batteries should not run down that fast.
What other programs do you have besides McAfee?
You could have malware.