I was never convinced that TRIM was actually working on my Crucial 128 M4. I did the "fsutil..." from the command prompt & got a "0", which indicated it was working. - Wrong!
I just recently found that TRIM actually was NOT functioning. Vladimir Panteleev just developed a simple tool called "trimcheck", which confirmed my suspicion - after running it - that TRIM wasn't working on my machine. This provided me the incentive to dig deeper, find the cause, & solve the problem.
Read my finding here: TRIMcheck: A FREEWARE TRIM TESTER
My post is under "TBoyd" on the page.
My problem may not be very common, but hopefully it can help someone else.
Please check out the latest article on trimcheck here: TRIMcheck: Does Your SSD Really have TRIM Working? | The SSD Review
Test your SSD for TRIM functionality. Trimcheck is a very small file to download & it is free!
Here's a direct link to the trmcheck utility: http://files.thecybershadow.net/trimcheck/