connected but no pages load after 10 minutes

Thought I should try this forum,might've been in the wrong one.The problem I am having is that after 10 minutes of the pc coming on and connecting to the net no pages will load up in mozilla firefox or internet explorer even though the pc maintains that I am connected to the net.I tried disconnecting and connecting again etc but that didn't help and I've found that the only way to get the pages loading again after it stops loading them now is to reboot.Then I get another 10 minutes or so net time before the pages stop loading again and I get the unable to connect to server page.Very frustrating as you can imagine.Any advice anyone can give would be greatly appreciated.

Oh here's some info about by computer:


Operating System Microsoft Windows XP Home Edition
OS Service Pack Service Pack 2
DirectX 4.09.00.0904 (DirectX 9.0c)

Motherboard
CPU Type Intel Celeron D 330, 2680 MHz (20 x 134)
Motherboard Name Gigabyte GA-8S651M-RZ(C) (3 PCI, 1 AGP, 2 DDR DIMM, Audio, Video)
Motherboard Chipset SiS 651
System Memory 224 MB (PC2700 DDR SDRAM)
BIOS Type Award Modular (07/15/04)

Display
Video Adapter SiS 650 (32 MB)
3D Accelerator SiS 315 Integrated
Monitor Philips 107E5 (GS4) [17" CRT] (CX 916294)

Multimedia
Audio Adapter SiS 7012 Audio Device

Storage
IDE Controller SiS 5513 IDE UDMA Controller
Floppy Drive Floppy disk drive
Disk Drive WDC WD800BB-00FJA0 (74 GB, IDE)
Optical Drive PHILIPS DROM5016 (16x/50x DVD-ROM)
Optical Drive PHILIPS PBRW5232L (52x/32x/52x CD-RW)
SMART Hard Disks Status OK

Partitions
C: (NTFS) 73053 MB (36904 MB free)

Network
Network Adapter SiS 900 PCI Fast Ethernet Adapter
Network Adapter WAN (PPP/SLIP) Interface (86.29.238.72)
Modem CastleNet 56K PCI Modem #2