What does "MIC error 603" on the Samsung M300 mean and how to correct it?

That MIC error means that the content being sent to the browser contains syntax errors and is not recognizable by the browser.

Possible causes are:

1. There is an incorrect internal browser setting
2. Invalid website URL
3. The URL might not be compatible with the phones’ browser
4. The specific web site is temporarily not responding
5. The specific web site is sending badly formatted data or content
6. The specific web site is unable to establish a secure connection

Unfortunately, there is no real fix for this. MIC errors are usually errors with the web site you are trying to access or simply that the web browser on the phone is not capable of handling that type of web site. source