I downloaded the CGP cell line project expression data and would like to convert the affy probes to official gene symbols. It's the HG U133A v2 platform and the dataset has a total of around 22000 probes. What's the best way to do this? I tried using IDconverter, but it froze after around 100 genes. When I used DAVID to convert to official gene symbol, the results only had about 9800 genes. Using DAVID to convert to entrez returned about 24000 ids, as for some probes, multiple entrez gene ids were returned. How should I deal with these duplicated entrez ids, or is there a better way to do the conversion altogether? Thanks!