Ben – you should bear in mind that PerfectForms, in design mode, is a full-fledged designer application and as such it does have memory needs. The tendency is for people to think that web apps do not need memory. I gather you have 480Mb total memory on that machine. The Form Player (the thing that handles form filling rather than completion) does not require as much memory as the form designer. We will be posting hardware recommendations shortly to avoid confusion.
Glad it is all ok now.