Romcenter

many of my roms have the same file name and expected name but it says that the specific rom is unknown and the file il signed red...although they work fine in MAME

That means the size and/or the checksum of the roms do not match the data, i.e. the roms are not correct ones according to the data.
And it is not strange that they work `fine' in MAME.

the size il always the same and the checksum in correct...i got the datafile from the mame i downloaded so it has to match...mame autid goes fine

anyway clrmame pro recognizes the roms that romcenter marks red well

There is a bug in size conversion. It occures on very big files afaik. See this thread.

in my set it affects many small and really small files

Can you be more specific and maybe post screenshots ?
Tell me which dat you are using and which files is concerned.