G/L Entries missing User IDs

Version: NAV 2009 R2 - RTC.

We have a bunch of entries in the G/L Entry table that have a special character and no User ID in the User ID field. The special character is a " &uarr " character (‘Up Arrow’ without quotes). I can’t notice any distinct patterns in the data. It’s happened with about 14 000 General Ledger Entries. Some of them are Gen. Jnls, some are Invt. Cost adjustments and some have no Documents- or Source- types and some don’t have Source Codes.

Has anybody experienced this before? I’m thinking it’s caused by custom development somewhere which could be quite difficult to fix.