There is a very large block of script at the bottom of the page source for wXw.pajacyk.pl. just before the closing Body tag, this is outside any of the other page formatting tags, etc.
This looks suspicious because of its location and also that the scripting itself appears to be obfuscated (disguised). The script tag also doesn't state what type of script it is, e.g. what script language, this doesn't conform with HTML standards, which the other scripts on this page do. Given that what this script also tries to hid what it is doing, unlike the other scripts on the page, so to me this is suspicious.
So this page might have been hacked and this code inserted.
I take it that this is the alert that you got, see image.
