After a while, the debug log goes crazy:
Chunks of debug log posted in issue #35 as I thought it was the same thing.

The value of X in "Client ack 15 exceeds server seq X" is sometimes different, I've seen both 2 or 4, once it starts it just keeps on endlessly till I restart Pidgin.

I can confirm I'm using the latest version, checked by re-downloading and calculating the MD5 sums for the in-use and freshly downloaded files.

(edit to add debug logs here)

Debug log.txt
This may be the start of one of the runaways:
Debug 2.txt