Consecutive 'SPOILER' and 'REV DISAGREE' EICAS messages upon setting takeoff thrust resulted in two rejected takeoffs and a return to the gate for maintenance for an E145 flight crew.

Narrative

We were informed by the inbound crew that the gate GPU was not functioning properly and that the aircraft was on APU power. I then performed a normal preflight inspection and found no abnormalities with the aircraft. The APU continued to provide electrical power to the aircraft during this time and at no point was the GPU selected. Gate departure and taxi out were normal. We were cleared for takeoff on Runway 35L. We performed a rolling takeoff procedure and I took control of the aircraft. Shortly after placing the thrust levers into the set thrust position; we received a master caution and 'Spoiler EICAS' message. I called for the abort and a standard rejected takeoff procedure was performed. Immediately upon reducing thrust; the caution message extinguished. I contacted Tower and notified them of the abort and reason for the abort. Once clear of the runway; we reviewed the event as a crew and referenced the manual. We observed no abnormalities from cockpit systems and decided the probable cause for the event to be that the rolling takeoff was performed at a higher than normal speed which caused a speed brake disagreement similar to a high speed taxi. We determined that it was safe to reattempt the takeoff. We were once again cleared for takeoff on Runway 35L. After setting the thrust levers in the set thrust position; we once again received a master warning and caution and now received the EICAS message 'E 1-2 Reverser Disagreement.' We immediately aborted the takeoff; cleared the runway and advised Tower we would be returning to the gate. Once again; as soon as the thrust levers were retarded; the alert was extinguished. Upon arrival at the gate; we notified maintenance and downed the aircraft. Both aborted takeoffs were performed at very low speed; occurring within seconds of placing the thrust levers in the set thrust position. The second takeoff attempt was made only because the alert had extinguished and we had no abnormal indications in the cockpit and had a logical explanation for the alert to occur. Upon completion of the second rejected takeoff; we determined that the aircraft may have a more major malfunction than we were aware of and elected to return to the gate and consult maintenance.