Unable to edit currency, tax, country after migration

[Lynnelle Richardson]

I upgraded joomla 1.5 to 2.5 and completed the migration from VM1 to VM2 as per instructions using VM2.0.0.  I installed the VM2 AIO file for the plugins however, I cannot edit/add any currency, tax, payment options.   All I get is a white screen with html links showing down the right hand side (same as what appears in the shop but not in a template design).

List of current tax & currencies appear where clicking on the links (RHS) when I click on the individual tax rates/currencies but I cannot edit them (goes to the white screen with html links).  Payment options screen is blank as if no options available and again white screen with html links appears if I try to add new payment option.

Has anyone encountered this before and how do I fix it?   Unfortunately, this problem has brought the design of the shopping cart to a standstill. 

Completely lost as to what could be stopping this - your assistance would be greatly appreciated!