Funny Problem - Repeated Update from VB will cause a particular row to be locked for days

We are using Informix IDS7.3UC2 on SCO Unixware 7.01. We are using UnBufferred Logging and found the following problems whenever we ran our VB5 programs. Repeated ( 2nd Update) on a particular row of a table causes the row to be locked. We are not sure how to remove the lock. However , we encounted this experience when we change the Logical Log Size from 210K to 64K it seems to work. We have to physically - i.e. unload the record and delete then reload the row again. This is very frustrating - IS there any body who knows what is happenning. THanks for your Input. Francis francis@jnesw.com.sg