disclaimer: I'm a relative newbie to wp & php but have been "enjoying" trying out different themes, widgets, plugins etc. without issue (other than figuring out where to control what in pagelines -- could that be a compatibility issue?) and wanted to find a free shopping cart solution for my non-profit client and this one came up first in the codex search.
each attempt to activate generated fatal error, out of memory. no login, no more dashboard.
as soon as I deleted it from my plugins folder, everything worked again. I repeated the installation, but same result.