Windows Advisor

Disk Cleanup Disaster Waiting to Happen; POP3 Errors in Exchange

Q: I ran the Disk Cleanup Tool and now Windows Vista won't hibernate. How do I restore it?

A: This is a known problem in Vista -- it happens when you run the Disk Cleanup Tool, which ends up disabling the hibernation file. That file needs to be re-enabled before your machine can go into hibernation mode or the hybrid sleep feature.

The Disk Cleanup Tool can be quite disastrous if it ends up disabling hibernation yet keeps hybrid sleep enabled. Many open programs that have automated backups won't have those files saved to disk when your machine does go to sleep.

If Vista is no longer able to hibernate, run the command powercfg -h on at the command prompt as an administrator. You can find more details in this Knowledge Base article.

Q: Why does the user name get rejected when some users log in to Exchange Server 2007 via POP3?

A: We're all familiar with the user principal name (UPN); it includes a user's log-on name, the @ symbol, followed by the domain name. Errors can occur when users have a UPN that exceeds 40 characters, which is the default limit for POP3 set by the MaxCommandSize setting. You can resolve this issue in one of two ways. The first method just increases the value of MaxCommandSize, this way:

  1. Start the Exchange Management Shell.
  2. Type Get-POPSettings to view current settings. You'll notice the default value is 40.
  3. To increase the value to 50 (the upper limit is 1,024 bytes), type Set-POPSettings -MaxCommandSize 50
  4. Restart POP3 for the changes to take effect.

The second method increases the value of MSExchPopImapCommandSize via the Adsiedit.msc snap-in. It's a bit more complicated, but it's covered in this KB article.

About the Author

Zubair Alexander, MCSE, MCT, MCSA and Microsoft MVP is the founder of SeattlePro Enterprises, an IT training and consulting business. His experience covers a wide range of spectrum: trainer, consultant, systems administrator, security architect, network engineer, author, technical editor, college instructor and public speaker. Zubair holds more than 25 technical certifications and Bachelor of Science degrees in Aeronautics & Astronautics Engineering, Mathematics and Computer Information Systems. His Web site,, is dedicated to technical resources for IT professionals. Zubair may be reached at


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