Subsequent to replacement of both ISIs; a CRJ flight crew rejected their takeoff due to a failure of the Captain's ISI and a STALL FAIL caution.

Narrative

Maintenance was on-board replacing a failed ISI (Integrated Standby Instrument). During the subsequent boarding process a STALL FAIL caution message and ISI failure were noted. Maintenance was notified and a logbook entry was made. Another ISI was replaced and the flight re-boarded. During the subsequent takeoff; a rejected takeoff was conducted due to no airspeed on the ISI and a STALL FAIL caution message. The lack of airspeed was noted at the 80 KTS call by the First Officer and the STALL FAIL caution message occurred soon afterwards. The aircraft reached a speed approximately 105 KTS by the time the rejected takeoff procedure was in motion due to delayed reaction. This delayed reaction was certainly associated with fatigue; frustration; the decision making process; and a 'double take' (verification by the Captain) that this was in-fact occurring. Air Traffic Control was notified of the rejected takeoff and the aircraft turned off the active runway.I believe this event occurred for a number of reasons. I think that both the Flight Crew and most likely Line Maintenance knew that changing out the second ISI probably wasn't going to rectify the problem. However; there were no indications prior to takeoff to indicate that the system was not functional and that the aircraft should not go. There was unwillingness by Line Maintenance to take the issue more seriously and perhaps look at a permanent fix for the discrepancy. There were also time pressures due to the late nature of the flight and desire to get the aircraft ready to complete the trip. There were fatigue issues on part of the flight crew (this being the last round trip of a four day schedule) and frustration with the deplaning and re-boarding that took place earlier due to the same issue.