Someone on another board had the same lot you have, and used it to begin his cycle. He told me it was fine, but then he switched to lot K, exp. May 2003 and it ruined his cycle.
I've come to believe that the lots with an expiration date of May 2003 are the bad ones, which would make sense since I believe these were the last lots produced before produciton of Aratest 2500 ceased. So the lot you have is probably okay.
On the other hand, Aratest is so cheap compared to the other components of a cycle that if it were me I'd just scrap the stuff and go with something else. I'd hate to ruin a $1,000 cycle over $50 worth of Aratest.
Rhino