Finder Trouble

Question

Last Monday, my iMac Intel Core Duo 2.4GH (bought late 2007), with 4GB RAM, suffered a weird breakdown.   Here are the symptoms:
Finder seemed unable to generate thumbnails for documents and the like. Once you open a Finder window, the whole machine slows down to near halt (you could place a mouse click every three or four minutes). With all Finder windows closed, the computer runs faster, but still much slower than usual, with apps notably too slow to start — though it does sometimes work smoothly. Neither re-launching Finder nor restarting the computer solved the problem. I tried to reinstall OS 10.6, but the operation failed (error, install process could not be completed). Tried restore from time machine, but the machine would not reboot afterwards. In desperation, I wiped out the hard drive and did a clean install of 10.6, then ran software update (back to 10.6.7 and all) and then restored my documents and stuff piecemeal (no full restore).  That seemed to do the trick.  The device was back running again like new.
Then this morning, in about the same the problem happened last week, it happened again.  Checking the Console I found an awful lot of messages like this one
“18/04/11 13:20:08 kernel disk0s2: I/O error."
followed by something that
“18/04/11 13:31:58 quicklookd[243] [QL] 'Creating thumbnail - cancelled' timed out for '<QLThumbnailRequest /Users/hazemeseifen/Documents/METS/WSD101005.doc>' (Start date: 2011-04-18 13:31:38 +0200)”.
So I’m pretty sure it is the disk I/O error that is causing the problem.  Any idea?  And keep in mind that I did a fresh system reinstall just a few days ago.

Answer 1

Hi Eseifan,
     Two scenerios in play here:
The file is a corrupted or complex file. That Console error message means that QuickLook Daemon cannot create that shiny little thumbnail preview. This can happen if the file is corrupted, not what it says to be or contains something within it that QuickLook cannot handle - such as Macros or Webpage links that need you to download things.
The HDD is bad. This is more serious. Basically your HDD has a physical defect and needs you to visit your local Apple Retail Store or Apple Authorised Dealer and get it replaced. Seeing as you have a TM backup, you should be able to restore if it is indeed a HDD error.
Try running Disk Utility, select Macintosh HD and click Repair Disk Permissions. This may help. Then run Verify Disk. If an error is returned, insert the installtion disc, restart, launch Disk Utiltiy and click Macinosh HD > Repair Disk.