Friend of mine had this exact same problem yesterday.
Delete the fh2 install you have now, then Update your BF2 to 1.5, reinstall fh2, and I bet it will work.
If that doesn't work try:
1) delete all the files it referenced in the error message. like the bf2.temp file. Browse to the folder that it tried to create that file in, locate the file bf2.temp, and manually delete it. Apparently if you CTD, it doesn't remove this file like it would on exit, so when the game tries to make it again, it cant, because it already exists.
2) Update your bf2. Chances are pretty high you are not on 1.5, or your 1.5 installation is borked.
3) Delete the FH2 mod in it entirety, you may need to boot into safe mode to do this. Run the installer for fh2 ad administrator.
4) If you use the old widescreen resolution fix in the shortcut after updating your bf2 to 1.5, REMOVE THE RESOLUTION FIX FROM YOUR SHORTCUT. 1.5 can natively support higher resolutions now, and having the shortcut fix for resolution, causes a conflict with 1.5 and makes the game either freeze at a black screen or CTD.
5) Run as administrator, and in win xp compatibility mode.