There is a page to allow a downgrade (back to 2.5.174 I think) and then you can upgrade from there. But I just can't find the page at the moment.
However, I am not certain that this is the problem. I am running firmware 3.0.52 and I just did a quick test using Twonky, although version 4.4.5 which is currently installed on my server. It worked fine using Browse Server Containers allowing me to search and find specific albums / songs etc.
Roku M1000, M1001, M2000, R1000, Roberts WM-201, Stream 83i