SDCARD Unmounts and Android Market Installation Error, Unknown Reason 18

With my new HTC Desire HD I was getting my SDCARD auto-unmounted and with the older firmware there was no way to remount it without pulling the card out and reinserting! This was causing problems with the camera (Please insert an SD card before using the camera) and other apps mentioned the SDCARD being busy or unavailable.

I was originally thinking that it could be a hardware issue but started suspecting the apps2sd functionality in android 2.2+ (aka froyo). Or perhaps some broken "Apps2SD" functionality in some of the market application managers...

Anyway I had the phone repaired for a different reason and it came back factory reset and with the latest firmware and it was still occurring!

However now I was also having a different issue with some apps not installing with an "Installation Error" dialog containing the text "Unknown Reason-18", as this was not all apps (or even most), I suspected that these might be trying to install on the SD card so I started doing some serious Googling...

It was suggested that you run this command in a terminal "rm /mnt/secure/asec/smdl2tmp1.asec", the trouble is that requires root access. In any case this sounds like a temporary solution.

Someone suggested that the solution is to put the sdcard into a card reader and attach to your PC and remove the "\.android_secure" directory (sorry can't remember if this is hidden or not), I did this and can now install the application "memento" and sure enough if you use Android's built in "Manage Application" and click on "On SD card" tab it shows that that application did indeed install on the SDCARD by default.

Hopefully this fix also gets rid of the intermittent card unmounts. I didn't have any apps installed on the SDCARD, if I had of has some then I'd probably have attempted to move them to the phone before trying either of the above.

UPDATE: It didn't fix my unmounting issue (and I just noticed the mount option is greyed out!). Anyway it appears that this is probably a known bug in the "1.72" firmware update! I've also noticed that when the card unmounts the phone loses cell radio signal (NO SIGNAL).

Since I've had the 1.72 firmware my phone has been rebooting overnight (I know as it wakes me up every time), taking a very long time to do so yet not updating the "uptime"...