TO run as administrator in 7, in Windows' Explorer you can right click the .exe file for the program & select Run As Administrator -- you can right click the .exe file, select properties, & then click the compatibility tab where there's a box to always Run As Administrator -- you can right click the link or shortcut for the program, click properties, and there's a checkbox to Run As Administrator.

Background...
Starting with Vista & continuing in 7, while your login account can be called an administrator, some permissions are still denied -- in effect you're not at the highest level, even as an administrator. This is important because many apps cannot fully access the parts of the Windows' Registry they need to. Running an app as Administrator gives it those permissions, & it's very common to need to run installations & some apps this way -- I can't run the latest Vegas 9C 32 in 7 64 without the extra privileges that come from running as administrator. Acid 3 & 7, Sound Forge 6 & 10, Vegas 7 & 9, DVDA 4 & 5, have all seemed to work better that way in win7 32 & 64 for me.

>"...Preparing & rendering are OK but when it comes to burning DVDA says to it will take 4 hrs, 6 hrs etc.
>It does not give any error phrase."

From posts I've seen it's much less common to have burning problems without some sort of cryptic error message -- the one's that folks have posted were unique enough to DVDA that using Google most of the first hits were relevant. Maybe the results you'll get searching on something like "DVDA burning problems Vaio" [w/out quotes] would bring up some suggestions, though trying it just now the 1st hits seem to ignore "DVDA"? Maybe win7's error message log would have more details? With that kind of projected time (hours) I wouldn't think DMA would be turned off for the burner [it'll slow things but not That much?], but it wouldn't hurt to check in Device Mgr. to make sure. Another thread had a post talking about DVDA taking forever to burn or prepare I think when USB storage was plugged in [in this case an mp3 player] -- USB storage device circuitry sort of *pretends* to be a hard drive as far as Windows is concerned, some much better than others... if you've ever tried to use conventional hard drive apps for backup, partitioning etc on USB sticks you might [unfortunately] know what I mean.

>"...But Nero 9 done it perfectly..."

TO be honest that's my preferred suggestion/solution (shared by many others), but some DVDA users don't like it -- maybe even why you haven't gotten loads of posts to this thread. I've found preparing to hdd has many advantages, like ease of burning duplicate discs later, & the option to edit DVDs in ways DVDA can't, plus I like using a specialized burning app [I don't use Nero to create DVDs, so why use DVDA to burn discs in place of Nero?]. Roxio works also -- I have their older EMC9 running in 7 32 & 64; many people seem like the Ashampoo burning app (you can usually pick it up free); ImgBurn is always free, & a standard for dual layer discs; Starburn [stand-a-lone or in other software] is popular worldwide [though some have prob with their virtual CD/DVD drive emulator driver]...