Scan multiple PDF Feature on Laserjet M1120n MFP

Hi, I have a HP Laserjet M1120n MFP and have just recently installed windows 7 on my pc which formerly had xp. After installing the full driver pack from the HP website the printer works fine except for the 'scan to' feature which behaves erratically. I have it set to scan to pdf which is how it was set before but when I go to scan multiple pages it sometimes comes out as just the first page, sometimes 2 instead of three and sometimes has two pages but they are both the first page.

Any ideas?

Thanks.