Server can need > 1.5GB Virtual Memory when uploading pictures

When I upload images via the Publish plugin in LRC to my Backlight 5 site, the virtual server at my ISP is giving errors that there is not enough virtual memory available (my plan allows me 1.5GB), and then seems to block my home IP address for a while (I can stlil view site via my mobile phone).

I am using the publisher v7.0 (as reported in LRC’s Plugin manager), and this behaviour seems ot have started about a month or so ago when I created new galleries of old scanned photos from my schooldays.

Please can someone give me pointers as to what I could look for regarding any of the images (e.g. size, type etc.), that might cause such problems.
Or, how could I rebuild my site from scratch again? (all pages are being built via LRC) so that I am starting with a vanilla Backlight 5 installation?

Many thanks,

You could try changing memory or upload limits in your php.ini file