I'm running avast professional editon version 4.8 build september 2009 4.8.1368 sometime's I get the same error seems to be when I send or try to send certain types of files/pictures/videos. I would not hold my breath waiting on a response from avast. they never did answer on a different problem I was having. I did get help here that lead me to resolution thou. turned out that avast had allowed over 1287 infections that avast would not detect. I ended up using malwarebytes Anti-malware free download to find and remove them all and had to turn off avast so it could work. It will work with avast if your not infected like I was. after I got my pc clean With malwarebytes anti-malware both worked fine together.
You may try downloading it and scanning your pc. It will find things avast does not. I had to run quick scan and full scan with it to completely clean my pc. more than once but it cleaned mine up finally heres the link I was given by pondus. hope you get it straight. and if you do figure it out email or pm me I'd like to know what was causing the trouble. it rarely happens to me so it doesnt bother me.
http://forum.avast.com/index.php?topic=53253.msg451454#msg451454The good news is that there are a few guys here like pondus and essexboy that are very helpful
If you run into a guy named tarq57. tell him to go away he will just try and make you look stupid for not answering his vague questions. Like he asked me what version I had posted 4.8 pro 2 or 3 times. he then tried to make out like I was vague. ANd if you were to read his post he never asked for the build number which he tried to make out like I was Avoiding posting this info he never asked for. asked me for logs that I couldnt post due to them being to large and trust me I tried.
hes just here to piss off people I guess just remember to avoid letting the blind such as he lead you.
I'm no expert but pondus and essexboy seem pretty savy. I'm sure there are others who are too. I just joined to resolve my issue yesterday after giving up hope on a reply from avast support. I'm using a paid version by the way.
best of luck