Kostika,
Convert your .mdb to .mde (Tools > Database Utilities > Make MDE file). The
..mde will have the full functionality of the .mdb but will not accept any
design changes.
Word of caustion: be sure to store the original .mdb securely so you can use
it to make changes if required, you won't be able to do it in the .mde!
It also helps to split your database into FE/BE (Tools > Database Utilities
Database Splitter) and convert the FE to .mde, so when you then make
changes in your .mdb and make a new .mde you won't have to worry about the
data being out of sync.
HTH,
Nikos