Later on in her dail Troia gets Barrier, but her range is 0. Does this mean that the entire barrier must be in squares adjacent to her? And if there aren't 4 squares together that are unoccupied, she can't create the Barrier?

It has to start in an adjacent square, there are rulings out there for this, most of them relate to Smoke Cloud thoughm but basically its the same ability.

Actually, if the character has a range of 0 then all the barrier or smoke cloud has to be adjacent to the character (not just one). This is what differentiates it from a range of 1. It's written this way in the consolidated PACs on the wizkids site.

I'd have to check but I think I'd rule that if there is not 4 consecutive adjacent squares to put the barrier in then the character can not put up a barrier (as the requirements for the barrier can not be met).

Yep, here's Chapeau's ruling which still stands I believe:
"Yep, if there isn't enough space for it, you can't make it. 0 means exactly that. Like close combat, 0 means directly adjacent."

well, but barrier allows you to just place one, then have it snake away...besides, chapeau is RETIRED. i d have to have a new ruling on this since troia s my poor man's wonder woman

It doesn't matter that Chapeau is retired, his rulings still stand (otherwise DrGandalf would have to go through all of them).

But I'm pretty sure the consolidated PAC on the wizkids site is enough to verify the intentions of the FAQ entry:
From the PAC: "if the character's range is 0, the markers must be placed adjacent to the character"
From the FAQ: "Characters with 0 range with Barrier must create the barriers adjacent to themselves"

I don't think we need to bother with a "new" ruling.

ah, thanks for pointing that out, so if there s even ONE opposing fig adjacent to me, that barrier is useless...hmm, well, JUST RUN, TROIA, RUN! to a medic, that is...

Gotta disagree here. If you read the unified PAC it also says that all 4 squares have to be within your range, while the FAQ says that only the first square has to be within your range.

So logically (and I know, logic doesn't always work on rulings) the same rules that apply to ranged barrier creation would apply to 0 range barrier creation - at least one square must be placed within the character's range, which in this case means adjacent. The point of contention (which will probably have to be addressed because of wording that can be interpreted either way) is whether the FAQ's adjacent means all 4 squares must be adjacent to the character or whether the barrier is adjacent to the character because the first square of it is adjacent to the character.

It's not useless. Here are several cases it could be useful (X's are clear, E's are enemies, T is Troia):

XXE
XTX
XXX

She can do this:
XBE
BTB
XBX

E and T are no longer adjacent. Or in this case:

XEXXX
XTXXE
XXXXE

She can create a barrier:
XEBXX
XTBXE
XBBXE

Blocking the other two E's from having LOF to her (for attack, outwit, perplex, probability control, etc).

dang, i hate it when people point out stuff to me that i could normally think of...*reaches for coffee...* thanks grinner!

The original PAC also stated that the 4 squares had to be within range. The FAQ adjusted this.

The range of 0 is a special case. And if you did allow her to start inside her range, her range is 0. A range of 0 is not an adjacent square (that's a range of 1), it's the square she's in. Since she couldn't put a barrier in the square she's in she would never be able to put down a barrier. Hence, the special case had to be made.

There is no contention. Arbitrers have ruled this way and the consildated (new) PAC and FAQ combined are pretty clear that in the case of a range of 0 all barrier tokens must be adjacent.

Canada Maestro is correct on all counts.

So what power in the comics does Barrier represent? I don't recall her having anything like that. And why does she lose it in later versions?

Well at least this one I know I can answer right

What we have here is yet another Titan whose rookie does not represent their early years with the Teen Titans (rookie Nightwing representing when Mr. Grayson quit being Robin and if the r/e/v Flash is Wally West the rookie represents when he got his own series rather than his Kid Flash days). While a r/e/v Donna Troy Wonder Girl have powers like her e & v versions, the r represents the powers she had when she first became Troia. Long story short (I know, too late), Donna found out she was raised by the Titans of Greek Myth. They gave her additional powers, like light and energy field generation. So the Barrier is actually an energy barrier.

She gave up all of her powers after the Lord Chaos/Team Titans mess that later tied into Zero Hour. Later, when it was revealed that she was a magical duplicate of Wonder Woman it was also revealed that while her Titan-given powers were gone her natural "Wonder Woman" powers were still there, which is why she is essentially a weaker Wonder Woman in her e/v versions.