Vista - help

I have windows vista, when i try downloaing programmes from the internet i
continue to receive a mesage from digital signature, then i am unable to
download the programme and it also happens when i try to use windows
upates.
Please can anyone help me to resolve this problem?


i tryed down loading msn i got wlinstall.exe publisher unknown
the file was blocked because it does not have a valid digtal signature that
verfiles its publisher click ok nothen happen
went to windows update got errors 80070570 and 8020053 can any one help me i
am running vista home prem and have rebote my pc and it kepps saying it