You're right about being old, when was the last time you open up the case and clean out your system?
It really sound like it might be over heating or the system is coming to the end of its life. If overheating isn't the problem then try cleaning up your drive and get rid of some unused files. Also go to microsoft and do a register clean up. Personally I would get rid of Norton. I've never had any luck with it. It would have been nice if you included your system specs.
AMD 7850 Black EditionX2 @2.8
Corsair H50 (CPU Cooler)
Power Supply Antec EW 750
Case Antec 900 II
XFX HD4850 (ATI)
2X2GB Super Talent and 2x1GB Super Talent Mem. moduals (6400)
Total mem 6GB
LG HL-DT-ST DVD/CD Burnner
Alpine 3 1/2 Floppy
Hitachi HDP725025GLA380 250Gb, 2 partions, SATA
Western digital WD2500AAJS-00B4A0 250Gb 2 partions, SATA
(each HD is partioned in half)
Network adapters Realtec PCIE GBE AND 1394 NET ADAPTER 2ea. (on mobo)
Ati High Definition Audio on Graphics card
Creative SB Audigy 2
All drivers are up to date:
Bios for mobo: F10A (newest bios)
OS Windows XP 32-bit Pro on my WD drive, Windows 7 64 Ultamate on my Hitachi drive.
Both are full versions.