AN explosion rocked the South African office of US software giant Microsoft on Friday, shattering windows but causing no injuries. “There was an explosion at around 5am this morning. Nobody was hurt,” Terry Annecke, marketing director for Microsoft’s South African operations said. She said the blast was caused by an unidentified device and occurred in the courtyard next to the company’s office in Johannesburg. Police were investigating. No staff, apart from four security guards, were in the building at the time of the explosion. Microsoft has recently embarked on a massive campaign against companies who use pirated software. There are also rumours that some staff members may be disgruntled at the recent drop in the Microsoft share price, after taking shares as a major part of their pay package.