Blank search causes error in in vq2-catalog search.php

Hello all

This is driving me nuts. My error log in OpenCart 1.5.6 is full of Notice: Undefined variable: results in /home/xxxxxxx/public_html/search/vqmod/vqcache/vq2-catalog_controller_product_search.php on line 517

I can replicate this by just click the magnifying glass in OpenCart, or pressing enter - both with the search box left blank - and the text above appears on the site. The error is also logged in admin of OpenCart error logs. I have tried removing every single xml file out of the VQMOD folder, emptying the vqmod cache - but the error still persists.

I just can't get to the bottom of this. We recently had to switch servers, and I am fairly sure that I didn't get this error appearing before then. I have the site sitting on a back-up server which is hosted by a completely different company, and although the error does appear in the log file in OpenCart on that version, it doesn't show up on the actual page the visitor is looking at should they accidentally press the enter key after leaving the search box blank.

A google search of the error shows lots of sites show that same result, so it is happening to others, maybe without them knowing. Any ideas?