Kroll is a pain and it's the source of a lot of anxiety. Everyone says that you have nothing to worry about if you didn't lie on your resume and application. That's true, but the source of anxiety comes from a bunch of hypothetical "what if" type scenarios that go through your head. It also looks like all major schools are using Kroll now (including UCLA, Berkeley, and Wharton in my experience).
In my case, one of the companies that I worked for went eventually went out of business. I left before they went out of business but I still had no HR phone number to provide in my application so I just wrote "N/A company went out of business".
When you fill out Kroll, you want to make sure that you write exactly the same info as you wrote in your application. Any changes and it's a red flag so I made sure that I did exactly that.
I filled out Kroll right away and they called my current employer about an hour after I filled out the web site (yes, they are fast!).
About a week later, I received mail from Kroll with their results saying that they couldn't get in touch with that company that went out of business. They also stated that all phone numbers on public records were incorrect since they were out of business. But they didn't explicity write that it failed or anything like that.
Everyone around me was telling me that it's probably not a big deal and I didn't think it would be either (after all, I had a plausible explanation). But it could be a pain to verify my salary at the time and bonus received, etc. if I have to try to dig up old tax returns or paycheck stubs, etc.
The problem in my case was that my school didn't notify me of the results for like a month! I know that I could have contacted them but I also didn't want to sound like I did something wrong (because I hadn't). But I was sweating bullets because it was taking so long. In they end, I didn't hear anything other than a simple "You passed the Kroll background check" and it ended at that about a month after I started the whole Kroll process. I heard cases where it was confirmed in a day or in a few days, etc. so it was making me more nervous. My recommendation for all schools is that if you're going to use a background check as the final hurdle for a student to get in, you should give your feedback to the student ASAP since this is such a topic of anxiety. I actually had about a week of sleepless nights over this because I was going through the whole scenario of "what if i fail? how am i going to explain this to work and everyone who thinks i'm going to business school, etc..."
RVD.