How did you change the icons did you change the system file or did you use that icon packer?
If you can you could try a system restore to a point before you made the change
System Restore
If that does not work or you do not have a restore point far enough back try Option 2 of this tutorial
SFC /SCANNOW Command - System File Checker it will not harm any data or programs you have installed but any customizing you have done to any system files should go back to default and if you used the Universal Theme Patcher to enable custom themes you will need to re-patch afterwards.
Let us know how it turns out.
Jerry
Edit: After you're done with the above you may have to do this
Icon Cache - Rebuild