I'd just like to say that, like member, etnies_boy, my ESET NOD32 anti-virus was throwing up a threat warning regards the Olmarik.ajl trojan, which it said it couldn't clean and didn't even appear able to quarantine. I contacted ESET for advice about this more than 24-hours ago and (so far) have received no response from them.
I resorted to surfing the web for help - and found Geeks to Go. I'm pleased to report that I followed the advice of member, Onaipian, and it seems to have solved the problem! To anyone else suffering a similar virus, I would therefore recommend reading the appropriate thread. It worked for me, even though I wasn't a registered member at the time and therefore couldn't post the OTL logs, etc, as requested.
Thank you, Mr Oniapian - you're a STAR!!!