You need administration rights to be able to serialize your plugins. If you are not an administrator on your workstation you can't install them.
In case you are an admin, here are some questions:
Have you updated your CS3 to 8.0.2
What plugins of Trapcode are you using ?
Where they working before ?
Have you installed CS4 products before install CS3 AE on your PC ?
Also, have you downloaded the current versions of the Trapcode plugins?
As the others already said - run as administrator. That is, if you are running Wind XP Professional. If you just run Win XP Home, then something else is afoot and you should provide some more info. The crash message is certainly related to the serialization issues, as this would attempt to open specific Registry keys that due to the failure in serilization never get closed properly. Could also be the Registration dialog or something with activation...