I ran into the same situation and I have not seen an actual resolution yet. I've been watching your thread waiting for a response that might also fix mine. Mine is working due to pretty much the same resolution you came up with. However, I have not had any problems on any machines as you have. I use the mscomm32 class and place it on my form. I got the idea here on the UT. Below is the oncomm event and a waitforresponse method I created to do the same thing:

*--MsCommContainer.OnComm()
*--Last Modified:
*--TCHolzer 01/22/2002  Trimmed extra characters from receive string
*--TCHolzer 01/31/2002 Corrected storing of input buffer to variable s for ON_LIST case
IF THISFORM.llescape
	RETURN
ENDIF
LOCAL ;
	i,;
	istop,;
	lnStart,;
	lnBegin
#define    ON_IDLE           0		&& dummy status to prevent onevent firing
#define    ON_STATUS         1		&& status of phonetree
#define    ON_SIZE           2		&& number of records in list
#define    ON_VERSION        3		&& phonetree version
#define    ON_MESSAGE        4		&& receive message from phonetree
#define    ON_LIST           5		&& List messages sent to
#define    ON_PUTMSG         6      && send messge to phonetree
#define    ON_PUTLST         7      && send list to phonetree
#define    ON_STOPCALL       8      && stop calling from list immediately
#define    _END_CHAR         CHR(10)
#define    _NULL             CHR(0)

this.creceivebuffer=""
this.creceivestr=""
this.lcstring=""
this.result=""
lnstart=SECONDS()
lnBegin=SECONDS()

IF UPPER(TYPE('OnCommType'))="N"
	THIS.oncommtype=OnCommType
	IF this.oncommtype<>ON_IDLE
		=this.waitforresponse(1)
	ELSE
		=this.waitforresponse(1)
	ENDIF
ELSE
	this.oncommtype=0		&& idle by default
	=this.waitforresponse(1)
ENDIF

LnBegin=SECONDS()
DO WHILE THIS.commevent<>2 .and. !thisform.llexit	&& if user presses escape, cancel and return
	=this.waitforresponse(1)
	IF SECONDS()-LnBegin>3
		IF this.oncommtype<>ON_IDLE
			*--Should have switched commevent to 2 by now, not receiving for some reason
			MESSAGEBOX('An Error Occurred with Phonetree.'+CHR(13);
		          +'Unable to get response.  Please verify'+CHR(13);
		          +'the Phonetree system is turned on and'+CHR(13);
		          +'try again.',48,'ERROR communicating with Phonetree.',50000000)
		ENDIF
		EXIT
	ENDIF
ENDDO
DO WHILE THIS.CommEvent=2 .and. !thisform.llexit		&& is user presses escape, cancel and return
	IF thisform.llexit
		RETURN
	ENDIF
	IF THIS.CommEvent=2	&& capture the information in this.input
		IF THIS.InBufferCount>0	&& received data
			*--If a message or a list was received, wait for the end of it
			IF this.oncommtype=ON_MESSAGE.OR.this.oncommtype=ON_LIST	&& receive message or receive list from phonetree
				lnstart=SECONDS()
				DO WHILE !CHR(26) $ this.lcstring
					this.lcString = this.lcstring+this.input
					IF this.lcString=="".or.alltrim(this.lcstring)=">"	&& nothing received!
						IF SECONDS()-lnstart>120
							EXIT
						ENDIF
					ENDIF
				ENDDO
				IF this.oncommtype=ON_LIST
					s=this.lcstring
					this.result=this.lcstring
					this.lcstring=""
				ENDIF
			ELSE
				this.lcstring  = this.lcstring + this.input
			ENDIF
			IF !(this.lcstring == "")
				this.result = ""
				*--we captured all of the data from the port, make sure it is not just
				*--an acknowledgement of a carriage return sent to phonetree
				IF ALLTRIM(this.lcstring)=">"	&& this is from all carriage returns sent to phonetree
					EXIT
				ENDIF
				i=1
				istop=(LEN(this.lcstring))
				IF this.oncommtype!=ON_LIST
					FOR i = 1 TO istop
						DO WHILE ASC(SUBSTR(this.lcstring, i, 1))!=0 .and. SUBSTR(this.lcstring, i, 1) != _NULL ;
							.and. ASC(SUBSTR(this.lcstring, i, 1))!=32
							IF SUBSTR(this.lcstring, i, 1) != _END_CHAR .and. SUBSTR(this.lcstring, i, 1)!=">";
								.and.SUBSTR(this.lcstring, i, 1) != _NULL;
								.and.ASC(SUBSTR(this.lcstring, i, 1))!=32
								this.result = LEFT(this.lcstring, i)
								i=i+1
							ELSE
								i=i+1
							ENDIF
						ENDDO	
						i=i+1
					ENDFOR
				ENDIF
			ELSE
				this.result=""
			ENDIF
			IF this.oncommtype!=ON_MESSAGE .and. this.oncommtype!=ON_LIST	&& receive message or list from phonetree, do NOT strip
			    FOR i = 1 TO LEN(this.result)
			    	IF ASC(SUBSTR(this.result, i, 1))=32 .and. i>1
			    		this.result = LEFT(this.result, i-1)
		    		ENDIF
		    		IF ASC(SUBSTR(this.result, i, 1))=13 .and. i>1
		    			this.result = LEFT(this.result, i-1)
			    	ENDIF
			    ENDFOR
			ENDIF
			DO CASE
			CASE this.oncommtype=ON_STATUS
				mPTStatus=this.result
			CASE this.oncommtype=ON_VERSION
				mPTVersion=this.result
			CASE this.oncommtype=ON_SIZE
				mPTSize=this.result
			CASE this.oncommtype=ON_MESSAGE
				s=this.result
			CASE this.oncommtype=ON_LIST
				*Do NOTHING s is stored above
			OTHERWISE
				*DO NOTHING
			ENDCASE
		ELSE	&& just in case only
			EXIT
		ENDIF
	ELSE	&& just in case only
		EXIT
	ENDIF	&& is commevent 2 or not, of not we exit the loop
ENDDO	&& while this.commevent=2
RETURN

waitforresponse:

*~ This method loops for the specified
*~ amount of time calling DOEVENTS().
*~ This allows time for the modem to respond to the requests.

LPARAMETERS lnDelayInSeconds

LOCAL lnStartTime
lnStartTime = SECO()


DO WHILE SECO() <= (lnStartTime + lnDelayInSeconds) ;
		AND NOT SECO() < lnStartTime
	IF thisform.llexit
		RETURN
	ENDIF
	DOEVENTS()
ENDDO
RETURN

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