>I found in the SDT.VCX where the table SDTMeta and SDTUser is opened (USE command). Now I am wondering, how I can prevent getting (rarely but still sometimes) a message "cannot read SDTUSER.CDX or SDTMETA.CDX".

Rather than trying to prevent the message, I'd try to fix the problem. You can build those tables into the EXE since they shouldn't change at runtime.

Doug