I got NS installed but now when the map changes in the game, my NS doesn't respond anymore, it gets to pending server info but then the game just locks up ? Anyone know what could be wrong?

not with out any info.

Steam, Won?
2.0, 3.0?
System Specs?
Freezes? as in your computer will not respond/sound loop? or just alt tab, or 3 finger salute?

ingeneral try these, but ALSO give us the info:
Reinstall ns/steam/hl(if won)
update Drivers/windows patches

give us INFO!

I got NS 3.0 latest version installed. Running on steam ofcourse. My pc specs are:
AMD Atlhon XP 1800+, 1024MB ram, geforce FX5200, Win XP + SP1 and updates. I got all the latest drivers. Reinstalling HL didn't work, i tried it :S

The game just freezes and doesnt repond to anything, my pc continues to run. What i do to close the game is ctrl alt del but that really pisses me off....

hmmm

/me ponders

you could try:
Reinstalling Steam
Deleating clientregistry.blob

realy don't know (these errors used to hapen alot, but then they were fixed so I am confuzled)

tried both didn't help