You've got the wrong forum for this sort of posting -- the proper place for this is;
When posting to the crossover forums, -please- mention your OS/platform/videocard specs,
as it's near impossible to help people without knowing this basic information.
There is no Assasins Creed 1 entry here in the codeweaver's compatibility database, so
your next best resource for getting info on this title running in the wine environment,
is over at WineHQ AppDB ...see;
Many of those tips are applicable to the crossover/wine situation -- for one, it looks
like you'll need to have directx runtime modern installed into the same bottle before
it will actually work -- it may need other dependencies, I am not sure...but I think for
sure you'll need directx runtime installed...
By your description however, it seems like you're running into a DRM CD-check issue long
before the actual game loads -- if you're on MacOSX this could be due to bugs/limitations
the the Mac scsi driver (known issue) -- if this is the case, please read carefully what
others have done to get this title running under wine on the above WineHQ page.