This is not exactly a simple fix, but it is a fix that works!
(1) if you are using dual monitors, SL must be on the primary monitor
(this usually causes a skin color problem and not the cloud avatar)
(2) the following will take you back to the original avatar and you
will lose any appearance changes,
(a) turn on the advanced menu item by typing alt-ctrl-d for
a pc or ctrl-opt-d for a mac
(b) select the following:
(i) "advanced"
(ii) "character"
(iii) "character test"
(iv) "test male" or "test female" as appropriate
(3) if this doesn't work, you have either a slow computer or a slow
connection