It seems our sql database is corrupted
Try unloading and then reloading the database - if that runs OK then the re-built database will be OK. Look at the docs for details of the dbunload.exe utility.

If you need more help then you can try posting on the dedicated SQL Anywhere forum http://sqlanywhere-forum.sap.com/, but don't forget that v5.5 hasn't been officially supported since 2002 - current version is v16!