Q: When I try to use the AOL software on my two Windows PCs, I get pop-up messages that say: "Either there is no default mail client or the current mail client cannot fulfill the messaging request." Because this never happened before, I assume it's caused by recent updates to either Windows or my Norton security software. What can I do?

Rich Mueller, Maple Grove

A: The updates aren't the problem. You received the warning messages because the old AOL software installed on your two PCs can no longer send or receive e-mails.

Earlier this year, AOL said it was discontinuing its older PC-based software and giving users a choice of how to keep using its service. They could either pay $5 a month to use new PC-based software called AOL Desktop Gold or use the free AOL websites (mail.aol.com or aol.com). The changes are occurring because AOL was acquired by telephone company Verizon, which is combining AOL's mail system with that of Yahoo, another acquisition.

As part of the change, previous AOL PC software has lost its ability to send or receive new e-mails, although it can continue to access old e-mails if they are stored on your PC (see tinyurl.com/y7ka33ox). As a result, you no longer have a working "default mail client," and that generated the warnings you received.

The most practical solution is to use one of the AOL websites via a web browser. (For an overview of the minor differences between accessing AOL via the Web rather than through PC-based software, see tinyurl.com/y8vphsyl). While this Web-mail approach may seem different, it's now common, and is the way people access popular e-mail systems such as Google's Gmail and Microsoft's Outlook.com.

Q: A friend of mine backs up all his files in Yahoo Mail and Gmail so he can access them anywhere, anytime. Do you recommend this practice?

Victor Moreno, Tucson, Ariz.

A: You can store documents in Yahoo Mail or Gmail by e-mailing them to yourself. But e-mailed documents won't appear in any particular order, so you can waste time trying to find the one you want to retrieve. A better alternative is to use a free cloud storage service (such as Dropbox, Google Drive or Microsoft OneDrive) that will store documents in alphabetical order based on their file names, just as a computer would.

Q: After I installed Windows 10 on my PC, my DVD and CD-ROM drive quit working. The drive appears in the list in the Windows 10 "device manager." However, when I insert a disk, the drive's light goes on but nothing appears on the screen. What's wrong?

Luana Goldstan, Reading, Pa.

A: The Windows 8 and Windows 10 operating systems don't include the software needed to play CDs and DVDs. Microsoft will sell you a $15 Windows DVD Player app that will enable Windows 10 to play those disks, but the app hasn't worked well for some users. You would be better off to download one of free disk-player programs instead (see tinyurl.com/yb2nqy4w).

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