I am using Version 1.3.9h of Zen Cart and for the past 8 weeks, have been running IH2 with no problems whatsoever

Yesterday to my horror, my site was killed. www.bestfeedsupplements.co.uk

I tried to restore from a back up but still I couldn't see anything under my category tabs.

I started to uninstall mods and got the store back once I uninstalled IH2

I haven't added any mods to the store in the past five weeks and am currently running
zen_lightbox-v1.6.2
multi_cross_sell_v1.00
GoogleAnalytics
google_merchant_center
Easy Populate 1.3.9gp
DPU2
corner_site_seal_1.0
autoTweet3
autoFacebook2

I thought that perhaps changing to IH3 might solve the problem and so uninstalled it as told, removed
zen_lightbox-v1.6.2 with an uninstall as well and then loaded IH3 according to the instructions
I then reloaded zen_lightbox-v1.6.2 to ensure that the correct code was used for additional_images.php was correct.

As soon as I installed IH3 in Tools: Image Handler3, my site went blank again

Now I realise that this cannot be a problem with IH3 ( I have another site www.equine-cortaflex.co.uk which runs IH2 perfectly and has not been affected in the same way - even though they run off the same servers (HostPapa) so does anyone please have an idea where I should look

I cannot see any obvious area where there is a conflict.

I will be quite happy to demonstrate the problem with installing IH3 and the subsequent loss of pages if it would help.