hi sargasso,
i just accessed yahoo groups with no problem.
i suggest you to delete all cached files and all cached cookies. they are in windows emporary internet files and windowscookies.
you should never disable the header filter "URL-Killer: kill a url". if you think it is the problem, well, here is what it does:
it scans all Adlists to kill connections with adservers.
if it causes your problem, then re-enable it and try to access yahoo group renaming one at time each of the 3 adlists: addomain, adhost and adpath to find the offending list (every time you need to clear cache). when you find the list blocking your access read all entries to find the offending entry.
obviously, if you remember the added entries, you can remove it directly.
i repeat myself, here all works nice, if you still have problems, i'll try to help you updating the filter set with the one i'm using now (release 2.50r).
regards,
altosax.