Can't enter back-end from the front-end on product screen

[Venkko]

Hi!

I can't enter to the back-end from the front-end anymore when I am viewing product details.
Mozilla just gives me empty page and Explorer shows me that this is HTTP 500 internal server problem (translated by me  )

I have J1.5.23 and VM2.0.0

any great ideas what I have done...

everything else seems to be working as they where before.

thanks

[Venkko]

I still can't go to back-end from the front-end.

ANY ideas how to fix this?