hey i have a canon powershot a640...and its on a 1 gb external memory card right now...since some time im not able to connect it to my laptop or pc ...the removable disk folder is displayed ,but when i open it it dosnt display any photographs...its just a blank file with one readme file named "bootex"...iv tried connecting it to several laptops and computers but still no luck...iv even tried taking out the memory sd card and putting it in directly into the computer but that dosnt help either...the folder is displayed but no photographs...but the photographs are displayed on the camera..could you help please..