Despite respectable sales in its first quarter of availability, RIM has reportedly slashed internal sales estimates for the BlackBerry PlayBook tablet. RIM announced during its earnings call last week that it had shipped 500,000 PlayBook tablets to retail partners during the fiscal first quarter of 2012. The figure didn’t quite match the 1 million mark that Samsung’s Galaxy Tab crossed after just two months, but it outsold Motorola’s XOOM tablet and beat estimates issued by several analysts. According to DigiTimes, however, RIM had very high hopes for its virgin tablet offering. The Waterloo, Ontario-based company had an internal goal of shipping between 2.4 and 2.5 million units during the second quarter. In light of lower than expected sales between the tablet’s launch in mid-April and the end of the fiscal first quarter, RIM has reportedly revised its second-quarter estimates down to 800,000 – 900,000 units.