This error usually occurs after WinZip Self-Extractor has created the EXE file you have specified. In some cases, when it attempts its final write to the EXE file (it does a check and then adds a CRC value) it is unable to do so.
The most likely cause for this would be an antivirus scan. If the active scanner (such as Auto-Protect with Symantec antivirus applications) is very sensitive, it may detect the EXE file and start scanning it before WinZip Self-Extractor has finished the final write. With this error, it would appear that the scan is also either locking the EXE file or temporarily moving it which causes WinZip Self-Extractor to be unable to Seek it.
You might try temporarily disabling your active antivirus scanner. If this allows you to create your self-extracting Zip file you can then assume that the active scanner is the issue. You should then check to see if you would be able to configure a folder that is an exception for the active scanner and use that folder as the location for creating self-extractors.
Please note that if you are using a Zip file located on a network shared folder, the self-extractor will also be created in the shared folder. In that case the antivirus application for the server (or computer) on which the shared folder is located will need to be configured. Alternately, you could copy the Zip file to a local drive and create your self-extractor there.
If you have any questions about this information, please submit a Technical Support ticket.