Since Malwarebytes (recommended above) got me out of a hole the other day - "see what's going on with AVG" I have been doing a little more work and discovered that fresh updates for this free software can be issued several times a day, so that if it needs to update and does, it is bang up to date. Other antispyware software does not update as frequently as this. Furthermore it would appear that any fresh download of this software is bang up to date - it doesn't have to upload the latest files of details of the layest spyware signatures. This means that, as happened in my case where a trojan was stopping my protection software from updating itself, a new download of this software stands a good chance of finding and eliminating such spyware.
P.P.