You looked to see if there's new drivers that work with SP2? You also looked at the manufacturer's website to see if there's any known issues with SP2? Probs a good idea if you haven't already.
mine router on wlan fked up recently, juski helped me sort it though (cheers fella), but they are a twat to back up n running when they go down for some reason, most times for me it tends to be the internal firewall on them
if u installed sp2 from the disk thats floating about, u probably have the first release of it. turn on updates and get the (massive) patch microslop released after everyone was complaining about sp2 i had a shit load of probs when i first installed it from microsoft and it was down to them making an arse of something. i ended up getting a patch through an update and it solved everything in one swoop i tried to uninstall it and it makes no difference at all cos sp2 changes core files, so u might aswell put it back in and get the patch from the updates hope this helps
good to hear its all back in order mate thought it might of been due to that additional patch they released
