Boots of Speed
As a free action, the wearer can click her boot heels together, enabling her to act as though affected by a haste spell for up to 10 rounds each day. The duration of the haste effect need not be consecutive rounds.
srd said:
Haste
...
All of the hasted creature’s modes of movement (including land movement, burrow, climb, fly, and swim) increase by 30 feet, to a maximum of twice the subject’s normal speed using that form of movement. This increase counts as an enhancement bonus, and it affects the creature’s jumping distance as normal for increased speed. ...
So it comes down to deciding whether crawling 5 feet as a move action equates to a crawl speed of 5 feet. In other words, is the normal speed of movement when crawling is 5 feet? If so, then it is 10 feet when hasted. If you feel it does not and that crawling 5 feet is not a "normal speed using that form of movement," then it does not double.
You could read it either way and be within the rules as written.
Sorry, there is no real clear answer, it depends on how you read crawling and haste together. Personally, I'd allow a hasted crawl speed of 10 feet.