I am using xperia x8 version 2.1 update 1.
Sometimes my phone creates problem with sd card i.e it automatically ejects stating "sd card unexpectedly removed" and after sometime it again shows "sd card preparing" and it works on. This distracts me to work in phone automatically the process gets delayed. I even tried by shutting down my phone, but the problem occurs.
Looks like the cause of you problem might be:
Try to use another SD card, if you get the same problems then I highly recommend you to flash a custom ROM like CyanogenMod 7 for example. Here you can get some tutorials about how to make it Update Xperia X8 with official firmwares or custom firmwares
I faced the same issue at least couple of times, but now its stable. I also have Android 2.1 update 1 version on my phone.
I strongly recommend you back up all your data (Call logs, Messages, Bookmarks, Contacts and Market Apps) to a PC.
After backing up your data try the following:
Reset the Settings (Settings -> Privacy -> Settings reset). It's going to restart the phone. Let it restart the phone.
If step 1 doesn't help then do factory reset (Settings -> Factory data reset). It's going to remove all the data from your phone.
If still no help then use Sony Ericsson Update Service to flash the Stock (Original) ROM into your mobile.
Please format, remove and reinsert the SD Card into your mobile.
You can try Nathan's solution, but your phone's Hardware should support the latest Android versions (>= Android 2.2) otherwise there are Custom ROMs.
As far as I know your phone's hardware won't support higher versions of Android. It allows you to flash the custom ROM but you will be able to use very minimal features of that Android.
This could be a hardware issue. If the SD card is continually failing / un-mounting like this, try another SD card, and try the first SD card in another device.
If the first card fails in the second device, it's the card. (Cards are cheaper to replace, so hope it's this.)
If the second card fails in the Xperia X8, it's probably hardware related. I would not root & mod to attempt to solve this problem as it's more likely to be hardware/warranty related.
I solved my problem by going to Settings -> SD card and phone storage and unmounted then remounting the card.
use the chkdsk method first insert your sd card in a reader then insert it in your computer then type cmd in start windows then run the cmd next type chkdsk /x /f then the card letter ex.chkdsk /x /f F: and then it will check the error and fix.
