I was flying the 757 today and I lined up to takeoff. Put in 50% power, then hit EPR, and it went as usual. At about 70 knots though, my throttles backed down to where my physical throttles were at, decreasing my power.

Then I manually increased my power again, but even at full thrust my 757 was not accelerating, and it was staying at 70 knots. I then braked and aborted takeoff, and then tried to taxi off the runway but I was stuck (it was like I had a parking brake on.) I went downstairs to check something and came back and I could only turn right. I'm wondering what just happened?