Microsoft has communicated a bug in all CTPs of SQL Server 2008 that is caused by “today”, February 29th, 2008:
We have recently discovered an issue with SQL Server 2008 CTPs that result
in SQL Server 2008 not starting or installing on Feb 29 GMT only. We
recommend that you do not run, install or upgrade this CTP on Feb 29 GMT to
minimize any impact in your environment. You can install starting on March 1
GMT. If you have an immediate issue that cannot wait until march 1st GMT
contact firstname.lastname@example.org before taking any further steps.
UPDATE: This bug is no longer in effect as we are now onto March 1st, 2008. For what it’s worth, the SQL team have checked the bug fix into the SQL Server 2008 code stream.