If you have any capacity Crucial M4 drive running firmware version 0009 or earlier you MUST update it to a later firmware state otherwise it will stop working after about 5100 powered-on hours (about 8 months at 24/7). Contrary to their comment below, it would appear (from a sample size of one, admittedly) that if you don't apply the firmware update *prior* to 5184 hours then you will NOT be able to do so afterwards, and you will then be the proud owner of a useless SSD.

You have been warned! Shame that Crucial couldn't be bothered to warn their customers - I certainly won't be buying their products again.

From http://www.crucial.com/uk/help/ssd/index.aspx?source=web
Release Date: 01/13/2012
Changes made in version 0009 (m4 can be updated to revision 0309 directly from either revision 0001, 0002, or 0009)
[Version 0309] corrects a condition where an incorrect response to a SMART counter will cause the m4 drive to become unresponsive after 5184 hours of Power-on time. The drive will recover after a power cycle, however, this failure will repeat once per hour after reaching this point. The condition will allow the end user to successfully update firmware, and poses no risk to user or system data stored on the drive.

This firmware update is STRONGLY RECOMMENDED for drives in the field. Although the failure mode due to the SMART Power On Hours counter poses no risk to saved user data, the failure mode can become repetitive, and pose a nuisance to the end user. If the end user has not yet observed this failure mode, this update is required to prevent it from happening.

If you are using a SAS Expander please do not download this Firmware. As soon as we have a Firmware Update that will work in these applications we will release it.

Included in the 0309 Firmware are the changes made in previous revisions.

I purchased this drive in mid-2011.

It failed after around 5800 powered-on hours (POH). Turns out that this is a well-documented bug in the design - see Crucial's website for details.

Crucial's response - do the firmware upgrade and the problem will be fixed. Except that's not the case - once the drive has 'died' in the way documented you cannot successfully upgrade the firmware.

I have returned mine to the ever-helpful eBuyer for replacement - I'll be checking the firmware release carefully!

Whay I found disappointing was Crucial's approach (knowing that they have a 100% failure timebomb in the pipeline) - do nothing and hope that customers put the blame elsewhere. Not impressed!

wonder what the return policy and data recovery policy is for the people that arent/werent able to update their FW in time.