AC Power adapter type cannot be determined, unique problem though

I've searched for the error message I've been getting but have yet to find someone with the exact same problem I have.  FYI, within the past year I've received both a new AC adapter and a new battery from Dell.  So onto the problem: ever since I received my new AC adapter, I've received the following error message intermittently:  "The AC power adapter type cannot be determined.  Your system will operate slower and the battery will not charge.  Please connect a Dell 65W AC adapter or higher for the best system operation."  Of course, a 65W AC adapter is being used.

 

In a separate but related problem, even when plugged into AC power, my computer will frequently not recognize this and continue running on battery power.  Even more annoying, there are days when it will be plugged in and just all by itself start switching back and forth, back and forth between battery and AC power.  It can just be sitting on a level surface, with nothing/no one touching it, and it will do this.  The worst part is when it switches back onto AC power and gives me the aforementioned error message.  Imagine coming back to your computer and having to click that error message 100 times because it's switched back and forth 100 times.  Heck, imagine it switching and giving you that error message when you're trying to use it.  There've been days when it's been so bad I finally just had to shut the computer down and not use it because I'd have to click that error message literally every other second. 

 

The problem, I'm sure, can't (at least entirely) be my AC adapter, because when I use my mother's 65W adapter, the problems decrease significantly in frequency and severity, but still occur nonetheless. 

 

I thought it might be overheating, but I've found after shutting the computer completely down and going to bed, in the morning the computer will be very cool but still give me the error message and switch back and forth between battery/AC power while plugged in.  I'm hesitant to call Dell Support (I'm still under warranty) because I just got my AC cord replaced, but if I can't find a solution I guess I'll have no other choice. 

 

Oh.  And getting my brand-new battery to charge for any significant period of time?  Fuggedaboutit.  Only occasionally have I been lucky enough to go long enough both without getting that "cannot be determined" message and my computer recognize that it's plugged into the AC power to charge the battery.