ok, If this happens with any other memory card, it seems like a virus problem. To remove the flag, follow these steps:
Go to command prompt, click on start, and then on run, and write on the promt the following.
attrib -s -r -h X:\autorun.inf
press enter and then write
You have to change the letter X, for the label of your SD card reader. For example, if your card reader is in the F:\ drive, you should change the lines to something like this:
attrib -s -r -h F:\autorun.inf
press enter, disconnect the card reader and then reconnect it. This should solve your problem.
I will recommend you to install some anti-virus software, for example Avast
which is free.