We will have to get more info about your setup.... Can you describe the topology of your network? Try to give the following:
-Who is your ISP?
-What TYPE of service? (cable or DSL)
-Are you using a router?
- How many hosts on the LAN?
- Are others having same trouble?
-Wired or wireless LAN?
- (wireless) what types of Wireless adaptors are you using?
- (wired)-Have you ensured that all cables are fully plugged in and not loose, and also not damaged?
- Have all drivers been updated to most current version?
- When trouble occurs have you tried to:
- Restart the modem?
- 'Repair' the connection through windows?
When problem occurs, per form the following and post the info up here...
START > RUN > type 'CMD' > type 'IPCONFIG'
Post up the IP ADDRESS, SUBNET, & DEFAULT GATEWAY