This could be a Launch Services issue. The following article describes how to
manually reset Launch Services — the notes at the bottom of the article also provide information about the side effects of deleting each of the files involved:
Resetting Launch Services
If you prefer using a cache cleaning utility instead of following the manual procedure described in the previous article, take a look at this other article for general troubleshooting and cache-cleaning procedures. Actually, you should also verify/repair the startup disk (not just permissions), as described there:
Resolving Disk, Permission, and Cache Corruption
The most appropriate utility for this particular problem probably is
Tiger Cache Cleaner, but you may also want to consider other utilities, such as
OnyX, or
Cache Out X, which are free. Whatever utility you choose, be sure to read this first:
Side effects of System cache cleaning
As an example, this is how you should proceed with OnyX:
1. Quit all applications.
2. Launch OnyX and enter your administrator password.
3. Go to
Maintenance > Reset and check
LaunchServices database.
4. Un-check any other pre-checked options.
5. Click the
Execute button.
6. Restart the computer.
BTW, if you’re running Mac OS X 10.4 (Tiger), as your profile indicates, it would have been more appropriate to discuss this in the
Mail & Address Book - Tiger forum. If the discussion applies to both Mail 1.x and Mail 2.x, it doesn’t really matter, but it’s difficult to know that in advance.