Something similar was reported earlier - and below is what the developer had to say:
"This happens when one changes the class structure of a shared object and restarts the L1 but not the L2. If this is not what he intends to do, he should probably restart the L2 after cleaning up the data file when he changes the class structure of shared objects. We do support some class structure changes like added a new field or removing an old field. This exception used to happen in one of those cases in 2.3 which got fixed in 2.4"
Does this apply to you - or are you already on 2.4
Thanks
Sreeni Iyer.