Anyone ever seen this error in the IDE:

Severity and Description    Path    Resource    Location    Creation Time    Id
Operator '50' does not exist for StringEvaluator    RtvDecisionEngine/src/rules/com/circuitcity/rtvcrms/rules    rtv.drl    Unknown    1179954317638    29080

And if so what do you do about it?  My rules file is just under 1000 lines [and growing] and shows no other errors.