Question: When I compile our project use Delphi 2010 Trial, there has a fatal error :

[DCC Fatal Error] F2084 Internal Error: L1737

Seem's a internal error. No hint at all. 

Is this a compiler bug or trial limit?

Thanks.

Answer: 
Make sure your paths are not mangled with those of older versions.  

Make sure you delete all the DCUs used in your project, included 3rd party components (unless you have some component without the source, in that case double check you have the latest DCUs for D2010) then do a build all to regenerate all those.  

Then try to cut your application in smaller parts and see what part is causing the problem: the goal is **to have the simplest possible application that triggers the error**, to be able to send it to Embarcadero with a reasonable chance for them to find the problem...
It means your code is too complex - Any file over a certain threshold in size (10k lines or so) starts to exhibit these problems - the other one is the 'was compiled with a different version of x' errors.

Although it's commonly said to keep related code in the same unit in delphi, it really doesn't scale so ignore that and break down as much as possible.