Do these switches have redundant power supplies? If so, is that what's showing as being down?  I experienced something similar on a 6509 - one of the power supplies had indeed failed but IOS saw it as "online" except it was actually not working correctly - even the LED on the physical PSU was fine. Orion said it was bad so I followed Orion and placed a call with Cisco and dug deeper with them only to find out it was actually dead in the water.  If you have SmartNet on one of those 3750's I would open a case with Cisco just to be sure - better safe than sorry

Thanks I was thinking along those line.

They are redundant, I was going to swap them out and see if the issue follows.

This might also be just a Cisco IOS bug. I've had a similar case with a 3750 where SolarWinds reported the PSU as Not Functioning but the output on the device is OK. Cisco have it listed under bug ID: CSCtx16194 with a fix in IOS 15.0(2)SE3.

http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCtx16194

The bug mentions only one PSU but in my case I had two with the second PSU marked as Not Functioning instead of Normal.

According to the bug report the following IOS versions are affected:

12.2(1)SE5  
12.2(35)SE  
12.2(35)SE1  
12.2(35)SE2  
12.2(35)SE3  
12.2(35)SE4  
12.2(35)SE5  
12.2(37)SE  
12.2(37)SE1  
12.2(40)SE  
12.2(40)SE1  
12.2(40)SE2  
12.2(44)SE  
12.2(44)SE1  
12.2(44)SE2  
12.2(44)SE3  
12.2(44)SE4  
12.2(44)SE5  
12.2(44)SE6  
12.2(46)SE  
12.2(46)SE1  
12.2(46)SE2  
12.2(50)SE  
12.2(50)SE1  
12.2(50)SE2  
12.2(50)SE3  
12.2(50)SE4  
12.2(50)SE5  
12.2(52)SE  
12.2(52)SE1  
12.2(53)SE  
12.2(53)SE1  
12.2(53)SE2  
12.2(54)SE  
12.2(55)SE  
12.2(55)SE1  
12.2(55)SE2  
12.2(55)SE3  
12.2(55)SE4  
12.2(58)SE  
12.2(58)SE1  
12.2(58)SE2

"Thank you so much for sharing the information. I researched on this issue for the problem you’re experiencing with power supply status returned incorrectly when you run snmpwalk, your 3750 IOS is hitting the bug id: CSCtx16194. Please visit the link given below for more information:- http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCtx16194 While your device is running 150-2.SE2, the fix is integrated in 150-2.SE3 and later. I checked few similar cases and the same has been confirmed by the backbone team. IOS 150-2SE3 has an ETA around May 2013. Unfortunately, there is no workaround for this issue. This happens randomly on some power supplies affected by this bug. You may try to reload the switch that shows incorrect status, but it may be a temporary fix."

I have had this too and I have fixed the problem by re-seating the power supplies one at a time.

There seems to be some logic in the power supply that gets reset by the power cycle.

I ran into this too.... If your 3750's are wired for redundant power, pull out the P.S. Health monitor is calling out.  Wait a few seconds, then push it back in.  This has worked several times for me.  I think it resets some type of logic circuit in the P.S..

I have found that on my switches with the issue code version the value comes back with a 6.. basically a removed PS. re-seating the PS normally clears the value and resets it back to a 2 or normal state.

known issue on Cisco.