Whenever I use IE 6.0 on my sisters desktop and open up 2-3 windows in IE6...without fail, the system stops responding after 10-20 minutes resulting in the ctrl+alt+del in order to close out IE6...Has this ever happened to anyone else out there??? Also, how do I correct the problem??? Thanks for any and all help

The Rig:

Lian Li PC-60 case w/Antec 400W UPS
Windows 98SE Most recent service pack
AMD TBird 1.4GHz/266 @ 1.564GHz/272 (GlobalWin FOP38 HSF)
512MB Crucial DDR266
ABIT KG7-Lite(Most recent BIOS ROM installed)
Diamond Viper V770 32MB TNT2 Ultra
Sound Blaster Live! Value
DLINK 530TX Ethernet
Adaptec 2940UW Pro
9GB and 36GB IBM SCSI HDD
12 GB Quantum HDD IDE (Backup only)
NEC 14X SCSI CDROM
Matsushita 8X/4X SCSI CD-R
IOMEGA SCSI 2GB Jazz drive (Backup)

Not a bad computer for a teenage girl huh?