irq 7, sound, parport and change of MAC address

[Monja]

Hello again :)
I read tons of e-mails here regarding irq 7 and the sound issue, so I
tried the workarounds described in
https://bugzilla.ubuntu.com/show_bug.cgi?id=1254
and in
http://wiki.ubuntulinux.org/WartyWarthog_2fParallelPortIRQ7
^^ here I cannot do step A,C,D and step B doesn't resolve my issue
(sound doesn't work, mixer not found, /dev/mixer doesn't exist)

no successs

But I discovered something: if I disable the parallel port or I write
pci=noacpi in grub menu...my NIC changes her (his?) MAC address!!
The two address are completely different, really strange isn't it? 

Anyone here obtained the same result?

I have a Dell Inspiron 510m BiosA06 

Thank you again for ubuntu!

Monja