I've been having an odd problem with my HP Pavilion laptop with Windows XP. It started happening a few days, without me having any added any new software or changed settings.

The computer freezes up every few seconds for a second or two, but never locks up completely. For example, when watching a DVD, the movie will stop for a few seconds, and continue playing and shortly freeze again for a few seconds. The freeze will sometimes briefly end with mouse movement, but the computer will shortly freeze again after a few more seconds. The clock is now also several hours behind, as if the computer is skipping. Similarly, when typing and the computer freezes, it won't type out the characters typed after the freeze as the case with most lock-ups. The mouse is also very sluggish because of the freezes, and its almost impossible to use the computer for anything. However, this problem only appears about 75% while using my laptop, and the other 25% it operates normally.

Thinking it might be a software problem, I used a recovery disk to clean out my hard-drive and reinstall Windows, but the issue was still there. The freezes seem unrelated to heavy loads, as CPU Usage is never even near 100% when they occur and memory usage is also low. I then considered that it may be overheating, but I downloaded a program to monitor CPU temperature and it seems to be in normal ranges. I thought the memory module(s) might have slipped out, but they appear to be in place. Are there any other causes anyone can think of? Anything would be greatly appreciated!!! Please let me know if I havent't explained the problem clearly.

The clock is now also several hours behind

This is probably unrelated to your freezing problems but should easily be fixed by replacing the battery. This is easy to do. Most likely the battery is a CR3032 (check number or manual to be sure) watch/camera type battery, $2 at Walmart. Just make sure you power down, AND UNPLUG the computer before reaching inside. Touch bare metal with your finger to discharge any static before touching anything else and pry out the old battery with your finger nail. Do not touch the new battery with your bare skin as skin oils attract dirt and promote corrosion. I put a clean sock over my hand. Make sure the rest of the interior is clean of dust and dirt and all fans spin freely while in there. Press on all connections before closing up to make sure all are securely fastened. While in there, inspect the motherboard for leaky capacitors. They look like tall soda cans, with many surrounding the CPU socket. There should be nothing that looks like white to dark brown dried foam leaking out the tops or bottoms. Bulging tops are a sign leakage is about to happen.

The first time you power up after replacing the battery, go straight into the BIOS menu and set the time and look at the hard drive settings to make sure it/they is/are correctly identified. Save and Exit and your time should be okay.

Now, for your freezing. This could be caused by several things, including an overheating or failing video card, failing RAM, failing or overstressed PSU, failing motherboard. Because the causes could be several things, troubleshooting is difficult. You already looked for leaky capacitors and seized fans. You can blast a desk fan in the side while using the computer to see if that helps if heat related.

Failing PSUs are hard to test - swapping with a known good one is about your best bet.

To test your RAM, I recommend MemTest86+. Select Download - Pre-Compiled package for Floppy (DOS - Win). Unzip the file to a convenient location, insert a formatted floppy disk in the floppy drive, double-click on install.bat to install. Then, with the floppy in the drive, reboot the computer. The computer should boot to the floppy and start testing your RAM. Let it run for several passes or even overnight. You should have no reported errors. Instructions to create a bootable CD version is available too. An excellent how-to guide is available here.