I had this problem when I reported a false-positive recently. The fp was resolved promptly by the Avast Customer and Technical Support but I had to log in with a different email account to my usual Avast! email one. It just seems buggy to login.
Buggy is certainly a good description I guess. I haven't been able to login to the Avast forum on the following browsers:
Firefox:
1) Cannot login to Avast forum
2) Could not login to "My Avast account", but later after logging in with the other two browser below I found I was able to login to "May Avast account".
Chrome:
1) Cannot login to Avast forum
2) Can login to "My Avast account" (but doing so doesn't help to login to forum)
IE:
1) Cannot login to Avast forum
2) Can login to "My Avast account" (but doing so still does not hep to login to forum)
Pale Moon:
1) Cannot login to Avast forum
2) Cannot login to "My Avast account"
I've tried to login into the Avast Forum with each of the four browsers above doing the following:
1) New Private Window
2) Restart with add-ons disabled
3) Start in safe-mode
All failed for a few days, however as of today I was able to finally login using IE (but only in "private window") and Chrome (but only in "Incognito") and I still cannot login or even access the forum in the 4 browsers in "regular" browser windows.
In some cases (some browsers) I can login to My Avast, but this still does not help regarding the Avast forum however.
In fact I cannot even access the Avast forum at all even in Avast's preferred browser Chrome as a "guest" since the links do not even work to open the discussion boards.
All very frustrating to say the least.