Having trouble installing Safari Extensions

[phytonix]

Problem:

Many extensions on extensions.apple.com cannot be installed.
However, extensions that I installed before, no problem, such as AdBlock, Bing, Echofon. Others, will not install, it will be stuck at installing. And Safari may lose response after a while.

I initially noticed that if I try to install YouTube5 which I downloaded myself, Safari will immediately lose response.

Tried solutions:

- Reset Safari
- Run OnyX
- Repair disk permissions
- Deleting all the extensions; extensions I installed before will install, others won't
- Deleting Clicktoflash and Glims

Still having the same problem. I feel desperate and helpless.
Any ideas?

 

[phytonix]

Update:

It seems if I let Safari to freeze a couple of minutes, the extension will eventually be installed.