Can't really help with the fix for the problem with Sveasoft, but would recommend a different third party firmware instead. Try
http://www.dd-wrt.com or
http://forum.bsr-clan.de/forum15.html for more information.
I did look at the SveaSoft firmware a long time ago, but the amount of controversy that popped up on the web around it (and the guy running it) put me off. Since then I've been using DD-WRT on my WRT54G for a home LAN with QoS to manage VOIP, UseNet and P2P downloads without any problems.