The startup grief I posted about last month was finally traced to an intermittent fault on my motherboard. Rather than throw any more money into a suspect system, I had a new computer built. The builder copied my existing hard drive (using Norton Ghost) so the desktop and applications look the same (and any errors in the software were carried over).

Even though it seems to operate fine, the Event Viewer shows three errors:
1 and 2) Two error entries for ati2mtag, and when I look at Properties for them they both show the wording 12c return failed. ATI is the manufacturer of my current video driver RADEON X550. (My former video driver was RADEON 9600 series).
3) One item for the Service Control Manager that says nvport failed to load. A Google search on this indicates other people are bedeviled by this one.

I update and run regularly Spybot, Adaware and AVG anti-virus (formerly Norton 2007). No problems found for years (except tracking cookies). No new hardware or software in last few months.

Any thoughts on how to get rid of these? (It does seem to operate OK in spite of these three errors.) Or isn't this a problem?

I'd think the errors would be because the hardware has changed but because the disk clone from the old computer was used, Windows is still looking for the old hardware. There may be leftover: 'Information - driver (or files to do with it) - Registry entries' that are to do with the old graphics card.

There are driver cleaner utilities that may help. Some are free, some aren't. Type 'driver cleaner' into a search engine to see what comes up. There could a risk of removing the current driver with such a utility though. So if you do decide to try this, make sure you have the driver handy.

Another approach might be to back up all your work, then format and re-install Windows (this would be my course if I'd bought a new computer).

Having said all that, if your computer is working properly, there's always the option of ignoring the errors. The Event Viewer in my computer shows the odd error message and warning, even though the system is pretty clean and fresh.