How to resolve “Virtual PC has detected an invalid or missing Product ID”

I’ve just installed Virtual PC 2007 on my work laptop (which runs Windows XP), and when I tried to start it, I got the following error:

Virtual PC
Virtual PC has detected an invalid or missing Product ID.

A valid Product ID is required to operate Virtual PC. Please
re-run the Virtual PC installer and enter a valid Product ID when

The solution is basically as described here, except I had to create the registry keys and values as they were missing on my machine.

Using ISAPI Rewrite to redirect to

My employer’s SharePoint-powered external website – which I look after – uses ISAPI Rewrite to provide “friendly” URLs for certain pages, and also to redirect old URLs to their new locations. Coming from a LAMP background, this is great for me as it basically works the same as Apache’s mod_rewrite.

Previously the website responded to requests for both and, which is not ideal. SEO best practice is to either redirect the non-WWW version to the WWW version, or vice-versa. In my case, is the preferred format, so I’m using the following rule:

### Redirect to
RewriteCond Host: ^domain\.com
RewriteRule (.*) http\://www\.domain\.com$1 [I,RP]

If you want to do the opposite, you’ll need this one:

### Redirect to
RewriteCond Host: ^www\.domain\.com
RewriteRule (.*) http\://domain\.com$1 [I,RP]

How to fix “Google Update installation failed with error 0x8004071c”

I just tried to install Google Chrome on my Windows 7 machine and was faced with this obscure error message.

I found the answer on the Chrome support site – it’s caused by the following registry key:


Mine was set to IMAGE_STATE_UNDEPLOYABLE. Removing this value enabled the Google Chrome installer to proceed as normal.

Geographical numbers for the AA

Buried in my AA (Automobile Association, that is…) renewal documentation, I spotted that they’ve provided land line telephone numbers as an alternative to the usual non-geographical 0800/0870 numbers, which cost extra from most mobile phones:

  • For breakdowns, the number is 0121 275 3746.
  • For membership enquiries, the number is 0161 332 1789.

Sites such as Say No To 0870 regularly publish user-submitted geographic numbers for many companies, but kudos to the AA for providing official numbers without having to jump through such hoops. Less kudos to them for taking 2 hours to tow my broken-down car, instead of the promised 45 minutes, but that’s another story.

Tame Access 97’s CPU usage

Access 97, for some unknown reason, seems to chew up all available CPU when it’s idle. Microsoft acknowledges this but has never provided a fix or workaround. It turns out this isn’t much of a problem – if you have other applications running which need CPU time, Access will gladly relinquish it. But PCs and laptops have evolved in the past 10 years, and often have variable-speed fans, which invariably sound like a cross between a vacuum cleaner and a jet engine when running at full pelt. Fortunately, there’s an unofficial patch available to bring Access’ CPU usage down to a more respectable level. Being unofficial, it’s of course not supported by Microsoft (or even the author of the patch), but it does seem to work fine on my system. The patch needs the latest Office 97 Service Release (SR2b), a 24MB free download from this MS page.

Quick tip: Printer paper orientation

I only use my printer occasionally, and it’s even rarer that I’ll want to print on letterhead paper or on the reverse of an already-printed page, so I often forget which way the paper should go in!

Fortunately most printers include one of the below icons embossed on or near the printer tray. The folded corner denotes the “top” of the page, i.e. where the letterhead would go, and the lines show which side will be printed on, so you know whether to place the paper face-up or face-down.

Beats trial and error!

Beats trial and error!

More details are in the post at Of Zen And Computing.

Quick tip: Fix noisy volume knobs

Lifehacker describes a quick fix for old volume knobs that cause static and popping when turned up or down. It sounds silly, but just switching the equipment off then turning the volume knob back and forth for a minute or so may get rid of most of the built-up grime that’s causing the static. I actually tried this the stock car radio from my twelve-year-old car and it worked a treat.