Hi Stephen - firstly this isn't a Catalook support forum - you should be using the Catalook site - http://www.dnnsoft.com for questions like this.
I have also got a support site for Catalook - http://www.catalooksupport.com - feel free to post there -
Next, you can't break your site/portals by uploading skins - no matter what the error is - you will NEVER lose your website by having installed bad skins or skins missing modules - if this ever happens, just overwrite the skin you uploaded via FTP and overwrite with a skin you know that works., and next - NEVER install a skin on a whole site without testing on page first - alway easy to remember after you've done isn't it.
Your comment about the time out - I've been working with Catalook store product since 2005, maybe earlier - who knows - and not had problems, BUT I can confirm with you that last week we have been trying to get a 4.8.2 build of DNN and a 5.0.6 build of Catalook to import and we've experienced problems - I don't know why- but I can tell you that I think there is a problem somewhere -timing out - application pool exceeding limits. I tried to analyse the differences with one site I've got that runs dnn 4.8 & Catalook 5.0.6 with no problems and the ONLY difference I could see was that it was an upgraded site, not one from new. I know it's not helping you but I can also confirm that I've had a bit of a challenge with Catalook and the same build you're talking about. We were able to import 5,500 products easily on another build, but the same file on the last version - no luck - Locally it works on latest, but live - I can't seem to get it to import at all. And Iv'e tried rebuilding the site three times now. Having worked with this application for so long, I feel confident in saying it's not you.
I have my own rack at a datacentre, so cannot talk about the resellerchoice hosting, but I do believe that they are not the cause of this problem.
Nina Meiers
Lots of FREE SKINS - really there
CatalookSupport.com - Another place for ecommerce support.