There are typically only three things that cause this situation:
1) You have clicked Forgot Password more than once in a short period of time, resetting the reset, and are using the wrong one.
2) Your browser is "helping" you with an Auto-Prefill feature that is "remembering" a different email address, password or both and overwriting them as you enter them. If this is the case, the solution is to COPY both the email address AND the temporary password from the email you received and PASTE them into the login fields.
3) You are using incorrect information - possibly even involving a typo. I know, I know....not you. But that other guy... he might have mistyped. We wrote this for him ;)
IMPORTANT NOTE: Passwords are case-sensitive - so make sure you are using the correct case.