Getting evaluation error on TC.getParam( ) after a long transaction

Hi, 

I am using LoadRunner 12.53 TruClient Firefox.  I ran into a strange issue where i am getting evaluation error when getting parameter value from TC library function. This happens only when the javascript is called after a long UI transaction that spins with a busy indicator for about 3 minutes. When I modify the input to the test such that the UI transaction only spins for about a minute, everything works fine.

This seems similar to an issue described here 
http://eyeontesting.com/questions/1351/loadrunner-truclient-ajax-failed-an-argument-is-in.html

Any idea why this happen and if there is a workaround for it?

Thanks!
Jason