on the site “secuser.com”, i saw that there was a security problem with avast 4.x (http://www.secuser.com/communiques/2005/050721_avast.htm)
what was the exact problem, and does the new version solve it ? Thanks 
Old news. Better read THIS and THIS. As you can see, using the latest version of Avast solves it.
IMO, I think that website make a big mistake by saying it is version 4.x which has this vulnarability.
There are several versions 4.x and the latest ones do not have this problem.
Saying version 4.x has it, is only confusing for users.
They should say something like 4.6.503 or 4.6.401 and earlier.
I hope that you don’t have to pay for that service as it is totally inadequate, especially when compared with the Secunia link Eddy gave or this one that gives a complete history on any vulnerabilities for Alwil Software and if they are patched, etc. http://secunia.com/product/5162/
;D no, i don’t pay for it ;D ;D
and i even don’t use it ! it’s a friend of mine who gave me the link 
thanks for your answers