Fixed a crash caused by an invalid index into plcfSpa.

Re-save in MS Word 2000 did Not fix the invalid index. A minor
modification followed by a re-save did fix it. Re-save in MS
Word 2003 did fix it. I decided to ignore such a floating object
- the test doc is huge and I could not create a simple test file
to propose a correction procedure.

Test document: esis.sc.egov.usda.gov%2FWelcome%2FFiles%2FESIS%20User%20Guide.doc