wierd session_start error

[chings]

I'm running 2 website in the same server ( winXP + Apache2 , PHP5)

All the file are saved under UTF-8 and the site are runnng well for over half year

today , something suddenly happened this morning , i found that the following error appeared in one of my site

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at D:\Apache2\htdocs\sms1\content.php:1) in D:\Apache2\htdocs\sms1\content.php on line 1

but another site work fine.

I didn't make any changes for the server setting nor the file, anyway , i checked the file again and make sure no space or any character before the session_start , it doesn't work , i had no more idea and tried to save the file in ANSI, it works again. but the file contains some chinese character and the website charaset must use utf-8 , so it's quite troublesome.

after 4 or 5 hours , i found another site has similar problem ( during the last 4 and 5 hours, it's running fine too) . the problem seems to be contagious. Under no good solution, i did the same solution

Does anyone meet the similar problem , i 'm so annoyed now.

[sid]

since the file changed out of the blue, could it be that your server was compromised? i've had it happen before, where a certain text editor would not show any whitespace before the opening php tag. however, when i placed the cursor there and hit delete, the file changed ("Save As" was un-greyed) and after saving it, the error was gone.

[Weedpacket]

Is this file being included by another? If so, then the character encoding of the other page must also be UTF-8; if it's ASCII text, then the content.php will be parsed as ASCII text as well - and the BOM will bite. I suggest you check that as well.