Help! My RNA has solidified!!

[wapling at staff.monash.edu.au]

I have been performing primer extension reactions on RNA extracted from gram 
negative bacteria using a standard heated phenol reaction - with TriZol 
from Gibco-BRL.

I am using 50ug of RNA in each PE reaction, and I'm finding that adding stop 
mix and heating at 80 degrees prior to loading, some (not all) of my 
reactions have solidified.

Reheating the reactions breifly will allow them to be taken up into a pipette, 
but they solidify almost immediately - usually part way between the pipette 
tip and gel!!

 Any suggestions as to why this is happening, and what I can do about it would 
be gratefully appreciated.