ZK - Open Source Ajax Java Framework

Hi
I am using Eclipse 3.5 with the newest version of ZK Studio on a Windows 7 32bit PC.
The strange thing is that ZK keeps disappearing from my workspace. It is shown as anabled in preferences --> Install/Update --> Available software and also listet in help --> About eclipse --> Installed software. But the Activate ZK studio menu entry is gone and there are no zk views available.
This happened to me before. At that time I had some other plugins installed and figured that it was a compatability problem between the plugins. Removing all the other plugins and reinstalling zk studio didn't work though. I then installed ZK Studio in a new workspace and i could activate and use it again for about two weeks. But today it disappeared again out of nowhere. I didn't install any new plugins or change anything regarding the eclipse configuration. I had only Java EE + Zk Studio intalled. Even installing it in a fresh workspace won't do the trick anymore.

Does anybody happen to have a solution to this?
Thank you!

edit: I tried both the online and offline installation, but that doesn't change anything.

"installed ZK Studio in a new workspace"????

Did you install a whole new eclipse?
Eclipse IDE for Java EE Developers (189 MB)??
Or simply changed to a new workspace?

Hi, thanks for your reply.
Workspace was realy a bad word choice, I was using a fresh Eclipse IDE Java EE installation.
But I have to apologize, I was frustrated because of some hibernate errors and didn't think straight anymore. After a restart I managed to confuse myself with the wrong eclipse installation, since I had configured the new one exactly as the old one. So I hope it keeps working now. Are most of you also using 3.5 or are you still on 3.4 because of other plugins?