System thrashing istelf accessing MAS90 db

[CrystalLion]

I am running reports using Crystal Ver XI accessing MAS 90.

I have no problem running a report that accesses one table, such as, the Customer Master table, as shown in the SQL Query shown below.

SELECT
"AR1_CustomerMaster"."CustomerNumber",
"AR1_CustomerMaster"."CustomerName",
"AR1_CustomerMaster"."SalesYTD",
"AR1_CustomerMaster"."DateLastActivity"
FROM "AR1_CustomerMaster" "AR1_CustomerMaster"
WHERE "AR1_CustomerMaster"."SalesYTD">.01

However, when I add another file, with an SQL Query looking like this:

SELECT
"AR1_CustomerMaster"."CustomerNumber",
"AR1_CustomerMaster"."CustomerName",
"AR1_CustomerMaster"."SalesYTD",
"AR1_CustomerMaster"."DateLastActivity",
"ARN_InvHistoryHeader"."CustomerNumber",
"ARN_InvHistoryHeader"."InvoiceNumber",
"ARN_InvHistoryHeader"."InvoiceDate"
FROM "AR1_CustomerMaster" "AR1_CustomerMaster",
"ARN_InvHistoryHeader" "ARN_InvHistoryHeader"
WHERE ("AR1_CustomerMaster"."CustomerNumber"=
"ARN_InvHistoryHeader"."CustomerNumber")
AND "AR1_CustomerMaster"."SalesYTD">.01
{ARN_InvHistoryHeader.InvoiceDate} >
Date (2005,12,31)

...the report trashes itself to DEATH. I have waited as long as 1 hour, and nothing.

Any thoughts would be greatly appreciated. Thanks

L