diff --git a/drv/commdrv.c b/drv/commdrv.c
index 1e0901a..cd97e1f 100644
--- a/drv/commdrv.c
+++ b/drv/commdrv.c
@@ -886,6 +886,18 @@ int16_t FAR PASCAL _export inicom(DCB FAR *dcb)
     port->is16550 = (uint8_t)detect16550(port->baseAddr);
     dbgHex16("KPCOMM: inicom is16550", (uint16_t)port->is16550);
 
+    // Disable UART interrupts and clear all pending conditions BEFORE
+    // hooking ISR.  Without this, a stale interrupt from a previous
+    // session fires the moment hookIsr unmasks the PIC.  The ISR sees
+    // isOpen=FALSE, skips isrDispatch, sends EOI, but the UART's IRQ
+    // line stays asserted (level-triggered ISA).  Result: infinite
+    // ISR loop, hard lockup.
+    _outp(port->baseAddr + UART_IER, 0);
+    (void)_inp(port->baseAddr + UART_IIR);
+    (void)_inp(port->baseAddr + UART_LSR);
+    (void)_inp(port->baseAddr + UART_MSR);
+    (void)_inp(port->baseAddr + UART_RBR);
+
     // Hook ISR
     if (hookIsr(port) != 0) {
         dbgStr("KPCOMM: inicom hookIsr FAIL\r\n");