Weel, first i have to agree, with the next reply, a dead loop in an interrupt routine is probably not a good ideae, but maybe you don't have much choice, and the problem is complicated to change the whole programm.

So maybe you can do something like this make your loop like this:

...
counter = 0
counter: add 1 to counter
check status of RI bit
check counter is equal to FF (or something)
if its equal go t oexit else goto counter
exit : reti

greetz Nico