Q. I run an email newsletter service for some local nonprofits, and I disagree with your column advising people to label unwanted email spam rather than click the unsubscribe link.

If a recipient labels one of my newsletters as spam rather than unsubscribing, it can cause their Internet service provider to block my Internet service provider. As a result, hundreds of other people who share that provider suddenly stop receiving the same email newsletter.

And there’s more. The Web hosting service I use to send out my newsletters also hosts many other websites, a few of which engage in spamming until they are discovered and shut down. As a result, if even a single person labels my newsletter as spam, my host can blame me for spamming, too, and shut down my emailing.

John Risken Minneapolis

In the online world, as in life, you are known by the company you keep. You should find a new hosting service — one that’s home to fewer spammers, thus has a better reputation. That way, other Internet service providers, and your own hosting service, will block you less often.

I continue to advise consumers to label suspicious email as spam rather than click “unsubscribe,” which can confirm their email addresses to spammers. This shouldn’t affect newsletters that consumers expect to receive; only the ones that they don’t.Q. Since I last updated Windows, I’ve started getting the error message “dwm.exe-application error.” I’m told this is probably a Windows Registry error, and that I need to clean the registry. What’s the best program to do that? I’ve heard some are just scams.

Lana Luhm Eau Claire, Wis.

There’s more than one way to fix the “dwm” error, which involves the Desktop Window Manager that creates special effects, such as transparent windows. First, try Windows System Restore, which will undo software changes made to your computer without affecting your data.

For Windows 7 or Vista, click the Start button, type System Restore in the search box, then click System Restore in the list above. On the following page, called “restore system, files and settings,” click next. Then check the box called “show more restore points.” Select a date prior to the update and click next. For details, see Microsoft’s support website at http://www.tinyurl.com/y9q9apj. For Windows XP, see http://www.tinyurl.com/ykgps6.

If no restore points are available for that time period, CNet.com lists free programs, at http://www.tinyurl.com/9ysygux, that will clean the Windows Registry, a database of configuration settings and options.