I purchased IconPackager10 a week or so ago and ever since I have had major problems with making icons stick after reboot, changing mp3 icon and the same icon would be applied to flac and other audio file types after reboot even though I have applied each extension its own icon. Icons to some extensions going missing an so forth . So me being me I wanted to dig and find out why. I started using lower res icons with smaller files sizes and iconpackager10 would behave much better. So this got me thinking could this be a problem with the windows icon cache? Seems M$ may have only allocated enough cache to support windows native icons. Now I'm not sure if windows deals with the icon cache dynamically but in my case if the cache is dynamic it certainly doesn't work for me. So to fix my problem I did the following.
Same old disclaimer applies... Play with your registry at your own will. I take no responsibility for any actions this may cause.
1. Apply Default windows icons package.
2. Clear icon cache
3. Open regedit and head to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
4. Right click New>String Value.
5. Name it "Max Cached Icons" (without quotes include the spaces)
6. Right click string select Modify and apply a Value of either 8192 (for hi res icons) or 4096 (for most other) hit return
8. Launch icon packager and apply you custom icons.
This method increases the System icon cache to either 4mb or 8mb and ever since doing so I have had no weird icon behaviour. All icons stick as they should. I hope this helps anyone who may have come across the same problems as I did.