NIS2005 network issues

Hi
I won't say how much I hate NIS or the none existent support but for reasons too boring I have to resolve this issue and would appreciate any pointers...

Norton Internet Security 2005, Win98
PC connects to Gateway no probs since install (had zonealarm free before)
but....

...mapped network drives fail to connect at startup NOW but will connect when double clicked in explorer once windows is fully loaded.

The network connections are now stupidly slow but the DSL connection is fine.

I have enabled inbound/outbound filesharing in the firewall settings...can someone tell me what else I need to do (no doubt it's obvious but my network knowledge begins to fail about here!). Clearly it's a firewall configuration problem as it was fine under zonealarm and goes away if I disable norton firewall.

Any help......cheers.