While your fonts work well with all of the other softwares, sometimes (on Tiger) word, excel and powerpoint 2004 tells you that all of your fonts are corrupted.

I almost found the solution in French here :

http://forums.macgeneration.com/vbulletin/showpost.php?p=3402399&postcount=2

1 – So, just restart your compurer and keep pushed the “Shift” key. You’ll start Mac OS 10.4 in a securised mode (no drivers, no preloaded softwares…).

2- Then empty you bin garbage.

3- Start Word, Excel and Powerpoint

4- Reboot.

After that, I didn’t encounter the problem any more.