Hi.
This can't be a coding bug. It must be because of the wrong configuration. At least i can say this: PureMart has nothing to do it.
You must have done something in the backend to force the use https:// in sensitive pages (even though you don't have a valid SSL)
Open the Virtumeart Configuration and check this:
Attachment Pasted_Image_5_9_14__7_14_PM.png not found
Regards.
Support