While I'm connected on the net and I download audio files from LimeWire 4.0.8, without doing anything else online in the same time, my computer suddenly turns off and restars by its own. Please inform me what is this and if there's any solution in my problem.

My computer has:

Processor: Intel Celeron 2.4 GHz
Math Support: On Chip
BIOS: Phoenix Technologies
Bus Type: PCI, ISA, USB, AGP
Ports: 1 Parallel, 2 Serial
Memory: 256MB
Video: NVIDIA GeForce4 MX 440 with AGP8X
Operating System: Windows98 SE, 4.10(Build 2222A)
Net Clients: Microsoft Family Logon
Connection: Modem ISDN in 64Kbps
Browser: Internet Explorer 6 SP 1
Jawa Plug-in: Jawa(TM) 2 Runtime Environment, Standard Edition 1.4.2_05
Antivirus Program: Panda Titanium Antivirus 2004

Thank you very much
PhotoreporterGR