Mbox (1st Gen) Windows Vista - crash error "c0000005" HELP Please !

[ze_lizhard]

Hi all,
I'm trying to instal my Mbox (1st Gen,focusrite...) with LE 7.4 on VISTA Home (previously I used 6.1 on XP).
Everything work fine, it finds the hardware...then when I restart the comp launching PT, I got this error "c0000005" :

(translated from italian..sorry for any mistakes! )

Problem Event Name: APPCRASH
Application Name: ProToolsLE.exe
Application Version: 7.4.0.309
Timestamp Application: 472841cc
Error Module Name: ntdll.dll
Error Module Version: 6.0.6002.18327
Timestamp Error Module: 4cb73436
Exception Code: c0000005
Exception Offset: 0003de2d
SO Version: 6.0.6002.2.2.0.768.3
ID local set up: 1040
Additional Information 1: e51a
Additional Information2: 4c0d4d78887f76d971d5d00f1f20a433
Additional Information 3: e51a
Additional Information 4: 4c0d4d78887f76d971d5d00f1f20a433

THANKS IN ADVANCE!!!!
Ze