Internal SQL Server error on view whose query runs OK

I have created the view shown below. Basically it gets totals of taxed and taxed deferred purchases. When I run the query itself (i.e. not creating the view), it works fine and I get about 1100 rows. The create view works fine (it creates the view). But when I try select * from _vwContribByRate I get:

Server: Msg 8624, Level 16, State 13, Line 1
Internal SQL Server error.

What's my problem?

create view _vwContribByRate as
select 'T' as taxable, c.socialSecurityNo, c.contribYear, rr.effDate, sum(c.payAmount) as purchAmount, sum(c.serviceCredit) as purchCredit
from tblPaActiveContrib c
join tblPaOHPRSrates rr on  rr.rateType = 'M'
    and rr.effDate = (select max(effDate) from tblPaOHPRSrates where rateType = 'M' and effDate < c.payDate)
left join tblPaServiceCreditPurchase p on p.purchaseId = c.purchaseId
    and (p.taxDeferred is null or p.taxDeferred <> 'Y')
where c.contribType in (2,4,6,7)
  group by c.socialSecurityNo, c.contribYear, rr.effDate
union all
select 'D' as taxable, c.socialSecurityNo, c.contribYear, rr.effDate, sum(c.payAmount) as purchAmount, sum(c.serviceCredit) as purchCredit
from tblPaActiveContrib c
join tblPaOHPRSrates rr on  rr.rateType = 'M'
    and rr.effDate = (select max(effDate) from tblPaOHPRSrates where rateType = 'M' and effDate < c.payDate)
join tblPaServiceCreditPurchase p on p.purchaseId = c.purchaseId
    and (p.taxDeferred is not null and p.taxDeferred = 'Y')
where c.contribType in (2,4,6,7)
  group by c.socialSecurityNo, c.contribYear, rr.effDate