I recently encountered some mysterious behaviour in Windows 7 (Home Premium 32-bit). Immediately after logging in (usually right after a reboot), the system would become almost completely non-responsive for about 15 minutes. And just as mysteriously, it would then return to normal until the next time I logged in, which could be several days later. What the heck was going on? Was this a Windows bug or something I had done? In fact, it was both…read on to find out the surprising solution!
With some patience, I was able to start the Task Manager and eventually the Resource Monitor during the 15-minute”lock-up”. Weirdly, the CPU utilization was quite low! However, the RAM utilization was 100%!I could see that the Windows Explorer (explorer.exe) was consuming huge amounts of RAM and generating a great deal of hard page faults (faulting to pagefile.sys). The “lock-up” was not for lack of CPU, it was due to massive amounts of disk I/O. This was confirmed by the disk activity light on the computer case being solid “on”. So what was causing this? And why would the system return to normal after about 15 minutes and then be fine for days?
I had recently installed a large application. Perhaps I had unleashed a virus? Some online research suggested that the Windows search indexer could be choking on an XML file. Sure enough, the new application had brought with it a bunch of XML files. So, I disable XML indexing. This didn’t solve the problem, so I disabled indexing altogether. Still no luck.
After living with this problem for a couple of weeks, I decided to go ahead with a planned upgrade to 64-bit. I presumed the problem would certainly go away with a clean install. Before reformatting the hard drive, I copied everything, including my desktop contents, to a backup drive so I could restore some of my settings after the re-installation. That’s because Windows 7 can’t migrate settings from a 32-bit installation to a 64-bit installation.
After the re-installation, everything seem good…no mysterious 15-minute “lock-up”. That is, until I tried to move my backed-up desktop contents to my new desktop. As soon as I selected the files and tried to drag them to the new desktop…WHAMO! 15-minute “lock-up” was back. What the hell?! Reboot, try again!
By trial and error, I was able to copy everything back to my desktop except one very large (2GB+) TIFF image. This was the problem! During a recent scanning job (at about the very time this “lock up” started, doh!), I had inadvertently placed a 2GB+ 48-bit, Lab mode TIFF image file on my desktop. It seems that whenever you login, Windows Explorer tries to process the files on your desktop. Even when you drop a file on your desktop, Windows Explorer tries to process that file, perhaps to build a thumbnail or something. The problem is if Windows Explorer finds something it doesn’t understand (like my huge, Lab mode, 48-bit TIFF image file), it can go completely nuts. And that’s what was happening. A bug in Windows and something I did that fell into the bug.
Conclusion: if you’re experiencing anything like the above, check to see what files are on your desktop and remove anything suspicious or out of the ordinary. Especially look for very large image files. It just might solve your problem.