I virtualize my firefoxes for a few years now but cannot figure out the following behaviour:

Firefox ESR 24.3.0 virtualized with ZAV 10 under WinXP. Works fine on XP machines. Visiting Adobe.com website under Win7x64 crashes it, other sites work fine.

Tried a very clean version without snapshoting (just extracted the firefox installer and used "add folder" in ZAV), which shows the same behaviour. Tried virtualizing it on a Win7 host, same effect. Tried the x86/anyCPU switch, no effect.

What can I possibly be doing wrong?
any help/comments appreciated