computer freeze ups

[mike13]

My Dell 4700 Dimension P4 computer is freezing up lately. I am running XP Pro with all the service packs. 256 Meg. of memory, and a 3.0 processor. I have AVG AV which I update and do a manual scan every third day. AdAware and Spybot are also run about every four days. The only things that load at startup are two items for AVG, one item for Cloudmark (a spam stopper for Outlook Express), and an item for Microsoft antispyware. If I do that Control Alt Del, (when it freezes), sometimes I can get to Task Manager. If I look at the Performance tab I see the CPU usage is about 50% when the freezeup occurs. Other times the CPU usage is between 0 and 10 %. Under the CPU usage is DF Usage which is 182 MB. Then there are four other areas below. TOTALS has Handles at 7183, Threads at 414, and Processes at 30. The next group is COMMIT CHARGE (k)with Total at 187,008, Limit at 619,385, Peak at 187, 680. The next area is PHYSICAL MEMORY (K) with Total at 251,980, Available at 36,650, and System Cache at 100,860 The last group is KERNAL MEMORY (K) with Total at 40,348, Paged at 34,992, and Non Paged at 5.356 I guess I could probably use more memory, but my other Dell 4600 never froze with basically the same programs and same amount of memory. . There was about three times when this freeze up was accompanied by a continous beep from the computer in the last two months. I e-mailed Dell since the computer is only about 6 months old. They responded that the beep usually means a hardware failure, and that the next time it happens, I should check the status of the four diagnostic lights on the back of the computer. Well, the computer still freezes up, but no more beeps. I have run the Dell diagnostics which takes about 90 minutes and everything checks out OK. I even ran the diagnostics at Pit Stop, and averything comes up OK. Very confused.
The computer has 256 MB DDR2 SDRAM at 400 Mhz. The freezeups always occur when using Internet Exployer or Outlook Express. In fact, a friend sent me a link to a special fireworks site. If I go there, and then click on the sky to make fireworks happen, the computer freezes every time. I tried it a few times. And I always had to manually shut down the computer. I was able to get to Task manager, but was unable to "End" any of the tasks. All help and suggestions are greatly appreciated