In the data flow tool container, i can't find the data reader source!why?and I encouter a problem when i use IS import data from Excel sources,I can't success import the data from excel2003 to sql2005,and the error is :

Information: 0x4004800C at Data Flow Task, SSIS.Pipeline: The buffer manager detected that the system was low on virtual memory, but was unable to swap out any buffers. 0 buffers were considered and 0 were locked. Either not enough memory is available to the pipeline because not enough is installed, other processes are using it, or too many buffers are locked.
Error: 0xC020901C at Data Flow Task, Excel Source [1]: There was an error with output column "ColumnName" (422) on output "Excel Source Output" (9). The column status returned was: "Text was truncated or one or more characters had no match in the target code page.".
Error: 0xC020902A at Data Flow Task, Excel Source [1]: The "output column "ColumnName" (422)" failed because truncation occurred, and the truncation row disposition on "output column "ColumnName" (422)" specifies failure on truncation. A truncation error occurred on the specified object of the specified component.
Error: 0xC0047038 at Data Flow Task, SSIS.Pipeline: SSIS Error Code DTS_E_PRIMEOUTPUTFAILED. The PrimeOutput method on component "Excel Source" (1) returned error code 0xC020902A. The component returned a failure code when the pipeline engine called PrimeOutput(). The meaning of the failure code is defined by the component, but the error is fatal and the pipeline stopped executing. There may be error messages posted before this with more information about the failure.



Information: 0x40043008 at Data Flow Task, SSIS.Pipeline: Post Execute phase is beginning.
Information: 0x402090DF at Data Flow Task, OLE DB Destination [14]: The final commit for the data insertion in "component "OLE DB Destination" (14)" has started.
Information: 0x402090E0 at Data Flow Task, OLE DB Destination [14]: The final commit for the data insertion in "component "OLE DB Destination" (14)" has ended.
Information: 0x4004300B at Data Flow Task, SSIS.Pipeline: "component "OLE DB Destination" (14)" wrote 22052 rows.

my data sources have more than 40,000 items,and the error cloumn is vchar ! i have modified the register key of excel TyoeGuessRows to 0!
before modified it it can import about 1,500 items!
pls help me!